In this paper, Monte Carlo (MC) technology with welding experiments and thermal simulation experiments were introduced to simulate the grain growth process in welding heat affected zone(HAZ) of 1060 industrial pure aluminum. First, a kinetic model was defined by both experimental and statistics method. Then the thermal cycle was calculated and at the same time the simulation program was worked out based on MC technology. Thirdly, the grain growth process in HAZ was simulated during different welding heat input, which has great influence on grain growth in HAZ. The result of the simulation demonstrates the grain growth process dynamically and embodies the “thermal pin effect”. Good agreement between MC simulation results and the experimental results was obtained which can provide a reliable evidence for evaluating the welding craft and the weldability.