The invention provides a biodiesel rectifying waste heat recycling system and process and relates to the technical field of waste heat recovery. The system comprises a rectifying tower, a steam generator, a biodiesel product tank and a water tank, wherein the rectifying tower is provided with a biodiesel steam outlet; the steam generator is provided with a hot medium inlet, a hot medium outlet, acold water inlet and a water vapor outlet; the hot medium inlet is communicated to the biodiesel steam outlet; the hot medium outlet is communicated to the biodiesel product tank; the cold medium inlet is communicated to the water tank; and the technical problem that in a liquefying process of existing biodiesel steam. By adopting the system, a lot of cooling water needs to be consumed, and release latent heat cannot be directly used is solved, and the technical effects of heating the cooling water by waste heat generated in the liquefying process of biodiesel steam to generate water vapor tobe directly used, reducing the energy waste and lowering the production cost are achieved.