Abstract: The high temperature stretching process of polymers is a crucial portion in the production of plastic geogrid, and the high temperature tensile parameters have important effects on the operation performances of plastic geogrid. By using high temperature and room temperature two-step tensile method, the polypropylene was firstly stretched at elevated temperature, and then the room temperature mechanical properties of the gained polypropylene samples were tested when they were cooled. The effects of tensile temperature, tensile rate, and tensile ratio at elevated temperature on high temperature and room temperature mechanical properties of polypropylene were studied. The results show that the high temperature stress decreased obviously with the increase of tensile temperature and decrease of tensile rate. However, the influence of tensile ratio was not evident. The percentage elongation after fracture at room temperature increased as the tensile temperature increased, while there was no notable variation with different tensile rates at elevated temperature. There were proper ranges for high temperature tensile temperature (110-130 ℃), tensile rate (100-250 mm·min-1) and tensile ratio (8~13) in order to make the polypropylene present excellent performances.