Abstract: On the basis of the co-control strategies,the algorithm of heat regulation is optimized for resistance spot welding by use of fuzzy control and single-chip computer technology.The monitoring mode of double-characteristics,dynamic current lag angle characteristic and dynamic current characteristic,is set up,and then the twice fuzzy decision-making method with multi-information fusion technology is applied in monitoring information,such as current lag angle incremental deviation en,heat percentage adjustment increment △m_n in present cycle,heat percentage adjustment increment △m_n+1 in next cycle and welding current deviation △I_n in present cycle.The results prove that this monitoring mechanism not only can be better control the direction and scale of heat regulation,but also can ensure the consistency of the quality of welding nugget and welding time.