Heckel is one of the main representatives of German Expressionism. His work spans six decades. Around 1910, five years after the founding of the artists' association "Die Brücke", a distinct group style was achieved, but Heckel soon abandoned it in favor of independent pictorial solutions. The pure colors are broken, the forms twisted. One senses a need for psychological penetration of the figures.
After World War I, Heckel develops a new, world-oriented classicism, which is accompanied by a greater closeness to nature and a brightening of the palette. The pictorial structure solidifies, the landscape watercolor becomes the preferred genre. In the late work one notices a stronger concentration on the two-dimensionality of the picture and a dampening of the coloration. The ornamental autonomy of the picture is given more weight than the reproduction of the immediate visual experience.