Abstract: The effect of mass fraction of hydrochloric acid, temperature and soaking time on the hydrochloric decomposition rate of thermoplastic polyurethane modified polyoxymethylene (TPU/POM) plastics with different formulas was studied. The optimum process parameters for the decomposition of the TPU/POM plastics were determined and the appearance of the sample after decomposition was observed. The results show that the decomposition rate of TPU/POM plastics sample increased with the increase of hydrochloric acid mass fraction, temperature and soaking time. The optimum process parameters for the complete decomposition of POM in the sample were listed as follows:the hydrochloric acid mass fraction of 20%, the temperature of 50℃ and the soaking time of 6 h or the hydrochloric acid mass fraction of 20%, the temperature of 60℃, and the soaking time of 2 h or 3 h. With the optimum parameters, the morphology of decomposed sample was changed to a porous cylinder shape with a smaller diameter from tiny particle shape with increasing content of TPU.