Abstract: A method of Monte Carlo combined with welding experiments was adopted to simulate the grain growth process in heat affected zone of a single phase alloy.Firstly,the kinetic equation of grain growth was built with the experimental data.The effect of heat pinning,the welding heat input,the peak temperature and the cooling rate were studied,which have great influence on grain growth in HAZ.Good agreement between Monte Carlo simulation result and the real experiment results was obtained.It can provide a good basis for three dimension simulation of grain growth in HAZ.