The invention relates to an automatic locking side pushing mechanism. The automatic locking side pushing mechanism comprises a clamp platform and I-shaped clamp supports located below the two ends ofthe clamp platform; the clamp platform is provided with a product fixing block, a first positioning block, a second positioning block, a first sliding clamping block, a second sliding clamping block,a first guide rail, a second guide rail, a first guide groove, a first pull block, a first air cylinder connection part, a second guide groove, a second pull block and a second air cylinder connectionpart. The automatic locking side pushing mechanism is simple in structure, smooth in action, and capable of enabling loading, machining and unloading to be coherent, working procedure and manual operation time can be reduced, work efficiency and operation safety are improved, the clamping platform is subject to platformization, the possibility that CNC sweeps fall in the dead corners is reduced,the sweeps can be conveniently recycled, the sweeps recycling rate is improved, resources are saved, and cost is reduced.