Surface composite reinforced with reactive process in-situ Al 2 O 3 particles fabricated through reduction reaction between melt aluminum alloy and CuO powder that coated to internal wall of the sand mold on the both of group casting alloys, pure aluminum and aluminum-11.2% silisum. Fabricated in-situ particles due to have not impurity in the interface of particle-matrix, have the good wet ability and coherent with the matrix in addition of increasing mechanical properties in the in situ composite rather than composite reinforced with the ex-situ Al 2 O 3 particles, to be taken improvement and increasing rate of nucleation from molten phase. In addition of the fabrication Al 2 O 3 in-situ reinforcement, a part of reduced copper inter the aluminum structure and with the composition of Al-Cu alloy in the surface of the as-cast, the surface of casting have treatment ability whereas internal sections of as-cast have not heat treatment ability. Whit age-hardening heat treatment on the condition of 535°C at 100 minutes for solid solution and 190°C at 8 hours for aging, CuAl 2 inter metallic precipitated beside the Al 2 O 3 particles, wear resistance of fabricated surface composite on the surface of Al-11.2%Si increased but in the pure Al as-cast sample is not improved. But reasonable to reduced the deep of valleys and wear particles in the both of alloy casting. The thickness of the composite layer on the surface of Al and Al-Si alloys was 50 and 75?m, respectively. Microscopic observation of worn surface for pure Al that casted in sand mold which coated with the CuO powder shows that with fabrication surface composite adhesive wear transform to mix of abrasive and adhesive wear. But for Al-11.2%Si alloy fabrication surface composite don’t change wear mechanism and the basic wear mechanism is delamination. Direct and alternative electric current used during the casting and solidification. The positive electrode connected to the metal mold and the negative electrode connected to the molten. Modification micro structure in the grain of Al and Si due to apply electric current during casting and with increasing strengths of the matrix, wear resistance increase for both alloy casting. Highest wear resistance make in the direct electric current and for alternative electric current, wear resistance is proportion to the intensity of electric current. Changing location of the electrodes in the pure Al don’t make sensible effect on the wear resistance but for Al-11.2%Si highest wear resistance is when the molten connected to the negative electrode and mold connected to the positive electrode. Apply direct electric current modified Al and Si grains and in the Al-11.2%Si alloy make three different micro structure that contain elongated Si near the negative electrode, fine Si grains in the intermediate section that the spherical Al-? surround them and comminute Si grains near positive electrode. Apply electric current in addition of modification micro structure cause increasing wear resistance of both pure Al and Al-11.2%Si that casted in the coated sand molds with CuO powders. At this condition wear particles is fin than the wear particles of pure Al and Al-11.2%Si that casted in sand molds which have not coating and the deep of valley in the worn surface is decrease. Key words Surface composite, in-situ particle, reactive process, age-hardening, wear resistance, electric current, modification micro structure