A poster designed by no less than nine prominent artists, with several elements from other posters, merged to a new composition. The quirkiest new element, at first sight: a man sitting on a missile, reading a book.

The image refers to the 'Eight Immortals' (八仙, Baxian) who in Daoist mythology crossed the sea using their 'power tools'. Li Tieguai used his iron crutch (compare the steel worker at the head of the group), He Xiangu rode a crane (compare the man on the rocket).
"Derived from this, the Chinese proverb 'The Eight Immortals cross the sea, each reveals its divine powers' (八仙過海，各顯神通 , ge xian shen tong) indicates the situation that everybody shows off their skills and expertise to achieve a common goal" (Wikipedia).

Sources:

Andreas Seifert, Christine Moll-Murata, Aufbruch ins sozialistische Paradies – Propagandaplakate
der frühen Volksrepublik China (Bochum: Ruhr-Universität Bochum, 2018) - online at https://www.rub.de/oaw/pdf/Veranstaltung/Katalog_Aufbruch_in_sozialistische_Paradies_web.pdf