The invention discloses a manufacturing method for automobile composite material plate spring preform. The manufacturing method is characterized by comprising the following steps of: uncoiling to form coiled fiber fabric; uncoiling and applying sizing powder, i.e., on a fabric conveyor belt, screening and spreading certain amount of sizing powder onto the fiber fabric through a screen; heating fabric to melt sizing powder, attaching the molten sizing powder onto the fabric, cooling the fabric, and enabling the sizing powder to solidify on the fiber fabric; stacking the fabric, i.e., cutting single-layer fiber fabric which is of different lengths and is added with sizing powder on the platform according to design requirements of a plate spring, and sequentially manually or automatically stacking according to a designed lay-up sequence; and pre-forming, and cutting single preform, i.e., cutting pre-formed large preform into single plate spring preform through a vertical type fodder chopper.