The present work focuses on determination of tensile properties of stone wool fiber reinforced high density polyethylene composites by two methods: experimental and finite element analysis. Four weight percentage of stone wool (SW) fiber 10 – 40 wt. % were chosen. The samples of composites were made by using the hot press technique. ASTM D638 was used to test the composite samples. Scanning electron microscopy analysis was carried out on the fractured surface to observe the interaction between matrix and fiber in the composites. Significant improvement of tensile properties was observed and recorded from the composites with SW weight percentage of 20 wt. %. The yield strength, tensile strength and tensile modulus increased by 8.1%, 23.0% and 37.8% over pure HDPE. ANSYS tensile models were then established to understand better the processing and behavior phenomenon. The numerical results obtained were in good agreement with the experimental results, with an accuracy of more than 90%.