Pyrolysis of polypropylene(PP) Was performed to find the effects of the pyrolysis temperature(425, 450, 475 and $500^{circ}C$) and the pyrolysis time(35, 50 and 65minutes), respectively. Conversion and liquid yield obtained during PP pyrolysis continuously increased with the pyrolysis temperature( up to $500^{circ}C$) and the pyrolysis time(up to 65minutes), especially these were more sensitive to the pyrolysis time at $425^{circ}C$ than other pyrolysis temperatures. Each liquid product formed during the pyrolysis was classified into gasoline, kerosene, light oil and wax according to the distillation temperature based on the petroleum product quality standard of Korea Petroleum Quality Inspection Institute. The liquid products of PP pyrolysis up to $450^{circ}C$ were almost same fractions($26{pm}3$wt.% gasoline, $20{pm}2$wt.% kerosene and $23{pm}2$wt.% light oil) except wax($3{sim}13$wt.%). On the other hand, the pyrolysis of PP from $475^{circ}C$ to $500^{circ}C$ produced $26{pm}3$wt.% wax, $24{pm}1$wt.% gasoline, $18{pm}1$wt.% kerosene and $16{pm}1$wt.% light oil. After all, the main liquid product changed from gasoline to wax with increasing pyrolysis temperature.