Abstract: CuZnSnSi alloy performs well on brazing steel.This paper aims at studying the thermal kinetics for the melting phase transition process with CuZnSnSi alloy as filler metal,by DSC and TG techniques and the differential and integral non-isothermal analysis methods.The results show that endothermic peak starts at 1150.5 K and ends at 1 221.5 K.The peak temperature of heat absorption is 1174.46 K.The endothermic peak in the heating process is lower than that in the cooling process while transforming without reaction,which indicates that undercooling is necessary to make the alloy crystallize.The calculated apparent activation energy is 615.72 kJ/mol and the transition rate varies withT as the function of k=1.71×1027exp(-6.16×10⁵/RT).