It can reduce the amount of residual oil and improve the total extraction rate of crude oil. Crude oil is treated by atmospheric distillation. According to the specified product scheme, crude oil can be divided into gasoline, kerosene, light diesel oil, heavy diesel oil fraction and heavy oil fraction. It can reduce the amount of residual oil and improve the total extraction rate of crude oil. Not only can more light oil be obtained, but also more raw oil can be provided for secondary processing and tertiary processing.