The luffing system of portal crane has a complex electromechanical coupling effect. In order to optimize the design of the electromechanical system, the electromechanical coupling dynamic equation is established. By taking portal crane of some models as the research object, the dynamic characteristic curve of the electromechanical system was gotten from combined simulation of the Adams software and the Matlab/Simulink software for the luffing system of portal crane under the rated load in the process of luffing. The rationality of the design of the electromechanical system has been verified.