The invention relates to a plastic film automatic covering system. The plastic film automatic covering system comprises a bottom plate, a mounting rack, an auxiliary device, a film covering device, and a feeding device; the mounting rack is arranged on the bottom plate; the film covering device and the feeding device are arranged on the lower end of the mounting rack from left to right successively; the auxiliary device is arranged below the film covering device, and is arranged on the bottom plate; the auxiliary device comprises a material loading mechanism, supporting columns, a supporting plate, an arc-shaped plate, an adjusting mechanism, and a spacing mechanism; the film covering device comprises a positioning adjusting mechanism, a laminating mechanism, and a cutting mechanism; the feeding device comprises a moving mechanism and a grabbing mechanism. The plastic film automatic covering system is capable of solving problems in the prior art that artificial cost is high, working efficiency is low, labor intensity is high, using range is small, and working stability is poor in conventional straw plate film covering process, is capable of realizing automatic film covering of straw plates, is low in artificial cost, low in labor intensity, high in working efficiency, wide in using range, and high in working stability.