After the revolution, Krymov took part in the Commission for Protection of works of art and antiquities of Mossovet (Moscow Soviet of People’s Deputies). Krymov was one of the founders of the magazine Put’ Osvobozhdeniya (“The Way of Liberation”), which was aimed to popularize the art among the soldiers. In 1919–1920 Krymov taught at the faculty of fine arts under Moscow Prechistensky institute of practical trainings, in 1920–1922 — at the Higher State Artistic and Technical Workshops (VKhUTEMAS), in 1920s — at Moscow Polygraphic Institute. In summers from 1920 till 1927 he lived and worked in Savvinskaya sloboda near Zvenigorod; since 1928 he spent summer months in Tarusa.

In 1921–1922 Krymov participated in the exhibitions of the group Mir Iskusstva (“World of Art”), in 1922 — in the First Russian Art exhibition in the Van Diemen gallery in Berlin.  In the same year the first personal exhibition of the artist was held in the State Tretyakov Gallery. In 1924–1925 works by Krymov were shown at the exhibition of Russian art in the Grand Central Palace in New York, in 1925 — at the exhibition of the Association of the artists of Revolutionary Russia (AKhRR), in 1925–1926 — at the exhibitions of the society Makovets. Since 1928 Krymov was a member of the Society of Moscow artists (OMKh).

The artist created scene and costume design for the productions The Cherry Orchard after the play by A. P. Chekhov (1922), The Ardent Heart by A. N. Ostrovsky (1926), Untilovsk by L. M. Leonov (1928), Talents and Admirers by A. N. Ostrovsky (1933) in the Moscow Art Theatre (MKhAT); Cupids in Small Bast Shoes after the play by P. S. Sukhotin (1927) in the Maly Theatre; Wolves and Sheep (1928) and Without a Dowry (1932) by A. N. Ostrovsky in the theatre Comedy (former Theatre of F. I. Korsh). Krymov designed performances for the 4th studio of Moscow Art Theatre (MKhAT) and music studio of K. S. Stanislavsky.

Since mid 1920s Krymov devised method for teaching landscape painting on basis of detection of tone relationships; he published several articles on this subject. In 1934–1939 the artist taught in Moscow Art College in the Memory of the Year 1905.

During the Great Patriotic War, Krymov stayed in Moscow because of his illness. In 1942 Krymov was conferred the title of the Honoured Art Worker of RSFSR (Russian Soviet Federative Socialist Republic). In 1949 he was elected corresponding member of the USSR Academy of Arts. In 1954 the second personal exhibition of the artist was held in the halls of the Academy of Arts in Moscow. In 1956 Krymov was conferred the title of the People’s Artist of the RSFSR.

Krymov was buried in the Novodevichy cemetery in Moscow.

Retrospective exhibitions of the artist were organized in 1967 in the USSR Academy of Arts, in 1984–1985 — in the Central House of Artist in Moscow.

Nikolay Krymov was one of the most significant painters of the first half of the 20th century; during his lifetime works by the artist were recognized as classical landscape. Krymov developed his own recognizable style of painting. He painted his early works as a mature artist. In 1900s he was interested in symbolism, that’s why his early works were characterized by decorative colours, lyricism, changeability of states of nature, of light nuances and air vibration. Later Krymov became interested in primitive art, theatre, classical landscape of the 17th century, impressionism, in particular the works by A. Sisley, E. Degas and C. Monet. In 1910s the artist left painting from nature and began to create his landscapes as Claude Lorrain and Nicolas Poussin.

It is difficult to mark out the certain period of art life of the painter. Although Krymov’s art changed in the course of time, but it always had inner wholeness and had no influence of environmental conditions. Working on the painting, the artist drew a lot of sketches, often on scraps of paper and lists from notebook.

Krymov handed down a great artistic legacy. The artist painted a lot till the end of his life. Works by Nikolay Krymov are in many museums of Russia and the near abroad, and in private collections. His works can be seen in many museums, insluding the State Tretyakov Gallery; the State Russian Museum; the Pushkin State Museum of Fine Arts; the A. A. Bakhrushin State Central Theatre Museum (GTsTM); the museum of Moscow Art Theatre (MKhAT); the Regional Museums of Fine Arts in Rostov-on-Don, Ulyanovsk, Tula, Bryansk, Nizhny Tagil; Astrakhan State Art Gallery named after B. M. Kustodiev; Saratov State Art Museum named after A. N. Radishchev; the National Art Museum of the Belarus Republic in Minsk; Kiev Museum of Russian Art; Odessa Fine Arts Museum and others.