The design and optimization of electromagnetic ultrasonic transducer (EMAT) is a multi-objective optimization problem, which has many variables, complicated analysis and great difficulty in optimization. By formulating the electromagnetic force acoustic finite element model of the electromagnetic ultrasonic transducer, the sample sets of the optimal targets such as Lorentz force, magnetostrictive effect, induced current density and vibration displacement can be achieved. In this way, the agent model of the multi-support vector machine is established. An improved NSGA-Ⅲ multi-objective optimization method based on the combination of reference point and congestion degree is proposed. The optimization design is implemented on the optimization target, and the most satisfactory optimization scheme is selected from Pareto solution set through the multi-index weighted grey target decision model. Compared with other optimization methods, the improved NSGA-Ⅲ algorithm is more effective for solving complex multi-objective problems. The rationality of the optimization process and the accuracy of the optimization results are evaluated by experiments. Results show that the detection signal of the electromagnetic ultrasonic transducer is increased by about 25% after optimization, which effectively improves the energy exchange efficiency. It provides a new way for the parameter optimization of the electromagnetic ultrasonic transducer.