The ordinary dryer barrel is made of single-layer iron sheet welded and surface painted, which is easy to dissipate heat. It uses a single type heating tube, and the working principle is to use an electric heating tube to heat hot air to dry the plastic particles in the hopper at high temperature, with the purpose of evaporating the moisture in the plastic particles. Slow heating efficiency, more prone to deformation and discoloration after prolonged use, and easy to contaminate raw materials after rusting.