A manufacturing process of EPC composite structure floors which includes an LVT layer and a substrate layer from top to bottom includes steps of separately and independently preparing the LVT layer and the substrate layer, and performing stacking and attaching the LVT layer and the substrate layer with glue so as to obtain finished products of the EPC floors. The substrate layer needs to be subjected to a working procedure of tempering before being stacked and attached with the LVT layer. The EPC floors manufactured by the process completely meet ISO standard requirements, and when being maintained in an environment of 80° C. for 6 hours, the WPC floors can also maintain a size change rate of 0.15% or below.