Preparation blend Epoxy, Polyester (EP95% , UPE 5%) reinforced by nano silica (SiO2) of grain sizes (30nm), Nano Alumina (Al2O3) of grain sizes (30nm) and short carbon fiber (C.F) With volume fraction 15%, for all prepared samples. Mechanical test (such as Tensile , Brinel hardness) was done in order to determine Tensile strength, young modulus, Tensile Fracture and physical test such as thermal and electrical (dielectric constant) in order to determine thermal conductivity and dielectric constant. The result shows that the addition of SiO2, Al2O3 and C.F to the blend (EP+ UPE) enchanted the mechanical properties at normal condition, the young modulus (E) is 36.1 MPa, and Tensile strength (T.S) is 7.80 MPa for blend (UPE5% EP95%). But these values changed with reinforcing to become 114.5 MPa, 16.61 MPa for sample A1, 601 MPa, 34.95 MPa for sample A2 and 394 MPa, 36.93 MPa for sample A3 respectivitly. the results showed that the high values hardness was for sample A1, A2, A3 than blend A. and the high values hardness value was for sample A3. About the physical properties, It was found that the reinforcing with SiO2, Al2O3 powder and short carbon fiber Lead to increased thermal conductivity (K)from0.282 W/m.oC for A to(0.321, 0.368, 0.518) W/m.oC for A1, A2, A3 respectivitly and while the dielectric constant (Ɛr) decreased and with changed from 1.5 to (1.49 , 0.95 , 0.94) for A1, A2, A3 respectively. .