A catalytic-esterification-free acid-degrading process for continuous production of high-acid-value waste oil and fat glycerin comprises the steps of raw material mixing and delivery, mixed raw material and finished product heat exchange, mixed raw material preheating after heat exchange, flash evaporation and dehydration of mixed raw materials, continuous esterification reaction and separation of glycerin extracted in the esterification process. The problems of low esterification reaction speed and non-thorough esterification caused by untimely reaction moisture discharging due to low reaction temperature in the process of preparing biodiesel by using high-acid-value waste cooking oil and leftovers in oil production industry and using methyl alcohol as an esterifying agent for pre-esterification and acid decrease are effectively solved, and the problems of device corrosion and environmental pollution brought by a large amount of produced waste acid water due to the fact that sulfuric acid is added to serve as a catalyst in the esterification process is solved. A continuous production process is adopted for esterification reaction, heat exchange of raw materials and finished products is achieved in the continuous process, and the problems of frequent and complicated operation, high labor cost, high production energy consumption, small yield and low efficiency of an intermittent esterification process are solved.