Characteristics and synergistic effects of the coliquefaction of Alaskan subbituminous coal, wasted tire, and polypropylene were investigated in a tubing-bomb reactor at 41$0^{circ}C$, and the coliquefaction reactions were performed at 37$0^{circ}C$~45$0^{circ}C$ to evaluate the coliquefaction mechanism. The coliquefaction kinetic model based on the free-radical theory was proposed and simulated by the non-linear parameter estimation method. Simulated results represented experimental ones successfully with the correlation coefficient of 0.99. When a catalyst was not used, the conversions were decreased as tetralin increase due to the decrease of liquefaction of polypropylene. When naphthenate catalysts of Mo, Co, and Fe were used, the coliquefaction conversions were increased with the increase of the liquefaction of polypropylene. When Co-naphthenate catalyst was used, the increase of the coliquefaction conversion were as high as 21~23%.