Cleaning agent for surface coating films of non-oriented electrical steels and cleaning method

The invention relates to a cleaning agent for surface coating films of non-oriented electrical steels, consisting of the following components by weight percentage: 2-10% of sodium hexametaphosphate, 3-15% of sodium carbonate, 8-20% of sodium polyphosphate; 10-30% of caustic soda, 1-3% of poly-oxylethyleneallkylphenyl ether, 0.1-0.3% of tributyl phosphate and the balance of water. Prepared preparation is poured into a cleaning groove and heated to 80-90 DEGC; electrical steel pieces with the coating films to be cleaned are vertically put into the cleaning agent, dipped for 30-50 s and then taken out; the surfaces of the electrical steel pieces are rapidly cleaned in the water and wiped by assisting while cleaning; and the coating films fall off fully. The cleaning agent is operated simply and high-efficiency and has no corrosion for the surfaces of the electrical steels so as to achieve the purpose of fully cleaning the surface coating films.