The invention discloses a control method of a slag removal system of an acetylene generator. For the liquid addition and slag removal of a slag removal system, the high pressure water washing of a slag removal pipe and a slag removal bottom valve, and the backwashing of an overflow pipe and an overflow slide valve, the manual judgment and operation is replaced by automatic control of an automatic control system; an onsite automatic control valve and pump start-stop control are added; the liquid level value, liquid addition frequency, and washing time are preset; when the program preset logic requirements are satisfied, the next step is performed automatically; at the same time, according to the requirements of product, the manual operation and automatic operation of the slag removal system can be switched; the program steps can be selected individually or together; after the program, all internal switches, valves, and pump positions are reset to the primary state; through the abovementioned operation, ideal control standards can be reached, the method is safe and reliable, the slag removal system of an acetylene generator can be controlled automatically, the operation is optimized, and the method can be widely applied to program control of slag removal systems of different generators in different chemical engineering fields.