The injection-rolling nozzle is one of the most important components in polymer's continuous injection direct rolling process. The basic theory for molten polymer mould channel design and the advantage of extrusion channels lead us to design a new channel for the injection-rolling nozzle. Simulation results show whether the channel structure design is feasible, and will allow the molten polymer flow to be even, yet also optimized for uniform velocity. The finite element method is used to optimize several key structural parameters for nozzle, which are then used as optimization object parameters. Compared with the previous results, molten flow velocity is more uniform after optimization. The velocity difference of 0·3 mm s −1 is slower at the outlet compared with 60 mm s −1 , and the total length of the nozzle has decreased. Finally, experiments results show that the channel with optimization has better flow speed uniformity.