The liquid scale model test is set up to research on the velocity characteristics of coupling airflows between subway piston wind and platform air jet. Model test and prototype meet the dynamic similarity. Piston wind variation rules on the test are validated with previous conclusions. The coupling airflows trajectory is closer to the horizontal direction with increasing piston wind. Under the constant air supply, the coupling velocities of measuring points increase with piston wind growing. The piston wind has more obvious influence on the coupling airflows than air jet.