This paper describes on the effect the ratio of fillers (Na10MB3A and CaCO3) have on the tensile strength of polypropylene (PP). These fillers have been added to PP in various ratios and mixed evenly before injecting. Experimental specimens are then made by the injection process under the same conditions including mold temperature of 600C, filled pressure of 200MPa, and injecting speed 110cm3/s using injection process. It was discovered that the tensile strength of PP increases gradually when the ratio of fillers increases. The results revealed that the tensile strength reaches its maximum value with a certain ratio of fillers, and thereafter the strength decreases as the ratio of fillers is increased. This research also indicated that the tensile strength of PP can rise by approximately 13.5% with the addition of Na10MB3A at a ratio of 3%, and increase to 21.46% with the addition of a 4% ratio of CaCO3. They are expected that experimental samples are the usefully promising materials for automotive components. In the future work, this study will further carry out an investigation into glass filler -reinforced PP and determine the fatigue life limit of the fillers-reinforced PP material.