Abstract: The simulation model of complete transmission path based on BGA solder joint was built by HFSS software, the return loss of complete transmission path were obtained based on the model. The impacts of signal frequency, solder joint maximum radial size, pad diameter and solder joint height on return loss were also studied. Taking the maximum size of the solder joint, solder joint height, the diameter of pad size as design parameters, the return loss as the target value, design and calculation of 17 sets of experiments using computational simulation. 17 sets of simulation of complete transmission path loss and the relationship between the parameters of BGA solder joint shape fitting by the response surface method, combined with genetic algorithm for fitting function optimization. BGA solder joint parameters with minimum return loss in full transmission path is the maximum size of 1.05 mm solder joint, height of solder joint is 0.75 mm, the diameter of pad is 0.65 mm, and the optimal combination of parameters of the simulation, the optimal combination of simulation results. The result of optimal combination is better than 17 sets of experimental results, and the optimization of the solder joint structure in the whole transmission path is realized.