Aiming at the phenomenon of clogging the nozzle of the wire material during the molding process of fused deposition technology, the idea of optimizing the size of the nozzle structure was proposed. Through the simulation of the temperature field of the nozzle outlet section, the orthogonal test analysis was carried out by combining the three factors of heat dissipation length, outlet length and convergence angle, and the optimal structure size combination of the nozzle was obtained. Comparing the actual printing process before and after the optimization of the nozzle, the surface quality and three-dimensional size accuracy of the part, the results show that the optimized nozzle can be used to significantly improve the accuracy of the part, and it can effectively reduce the probability of wire clogging at the same time.