This research aims to study the effect of addition the filling materials (sodium aluminosilicate, Talc) to the unsaturated polyester(unsaturated polyester resign)(UPR) first, and unsaturated polyester reinforced by fiberglass (20%) secondly, Number of mechanical tests were done, they included (Tensile, Flexural Strength). The effect of addition of filling materials sodium aluminosilicate (SAS), Talc, and a mixture of sodium aluminosilicate and Talc to the unreinforced polyester with fiberglass was studied in the first step of the research, and the results showed that the best values were gotten when adding a mixture of ((SAS) and Talc) at ratio (10% SAS,5% Talc), where the tensile strength value raised up from (31.2 MPa) to (33 MPa), and the elastic module value also raised up from (2330 MPa) to (2750.5 MPa) , and the flexural strength value also raised up from (0.057 GPa) to (0.0729 GPa). The effect of addition of filling materials (sodium aluminosilicate, Talc, and a mixture of sodium aluminosilicate and Talc ) to the reinforced polyester with fiberglass (20%) was studied in the second step of the research, and the results showed that the best values were gotten when adding a mixture of ((SAS) and Talc) at ratio (5% SAS,5% Talc), where the tensile strength value raised up from (101.7 MPa) to (108.8 MPa), and the elastic module value also raised up from (5616 MPa) to (6367.9 MPa), and the flexural strength value raised up from (0.1203 GPa) to (0.1597 GPa).