Abstract: In order to increase efficiency and improve quality of heat exchanger in air condition further, simulations of Aluminum brazing sheet cruciform joint based on VOF 3D model were carried out to research the wetting process of filler metal under different brazing temperature and joint gap. Meanwhile, experiments were conducted. The results show that the model can simulate the flow and shaping of joint approximately and predict the influence rules of temperature on wetting length, which validates this model. Brazing temperature affects the shaping of joint considerably. Compared to 600℃, 590℃ and 610℃ both led to the decrease of wetting length due to insufficient wettability and running off increasingly of filler metal, respectively. Too little gap generated aggregation of filler metal at bottom of joint and too large gap weakened capillary action, both of which went against the wetting of filler metal. So symmetrical gap for the joint is best.