The invention relates to a construction method for an environment-friendly light concrete cushion. The construction method includes the following steps that a ground base layer is cleaned; an elevation is set, ash plates are manufactured according to the set elevation, and the distance of the ash plates is not larger than 2 m; water is spread on the ground base layer for moistening, and plain cement mortar is swept to form a combination layer; environment-friendly light concrete is poured on the ground base layer, and the environment-friendly light concrete is formed by stirring cementing materials, aggregate, light aggregate and water; the light aggregate is water granulated slag; rubbing, pressing, compacting and leveling are conducted; the poured environment-friendly light concrete is rubbed, pressed and compacted, leveling is conducted through a scraping lever, and flat rubbing is conducted through a float; secondary flattening is conducted before the environment-friendly light concrete is finally set, and roughening is conducted; the environment-friendly light concrete is maintained. According to the construction method, a series of construction problems that a traditional ceramsite concrete ground technology is complex, particles float, and compactness is poor are solved; in addition, environmental friendliness is achieved, construction is convenient, time and labor are saved, the construction quality can be ensured, a construction period can be shortened, and investment can be reduced.