The invention discloses an assembly type cushion structure used for a foundation pit project and an application method of the assembly type cushion structure. The assembly type cushion structure is installed at the soil inlet point position of an inclined support in a foundation pit and specifically includes at least two horizontal base plates which are oppositely spliced. The splicing faces of the horizontal base plates are matched with the outer wall face of the inclined support. A half-circle hoop is fixed along the splicing faces of the horizontal base plates. The assembly type cushion structure has the beneficial effects that the assembly type cushion structure is simple, construction of a cushion can be rapidly completed after a foundation pit is dug to the bottom, the function of the cushion is developed, the cushion participates in bearing and dispersing the loads of a pit edge immediately, deformation of the foundation pit is relieved, the purpose of controlling the deformation risk is achieved, and the assembly type cushion structure can be recovered and recycled.