Stir casting method is one of the methods used to manufacturing AMC. Parameters in the stir casting method that must be considered when manufacturing composites include stirring temperature, stirring speed, and treatment of reinforcement particles which will affect the mechanical properties of the composite. This research was conducted to determine the effect of electroless coating treatment on hardness and tensile test of Al 6061–SiC and Al 6061–Al2O3 composites. The process of manufacture composites used agitation at a temperature of 720–740 °C, stirring speed of 600 rpm, and electroless coating of reinforcement particles on SiC and Al2O3. The results obtained are even distribution of reinforcement particles through the electroless coating treatment. The hardness value on composites with reinforcement particles through electroless coating is 54,52 HBN for SiC and 52,52 HBN for Al2O3 and hardness value in composites without electroless coating treatment was 51,16 HBN for SiC and 50,40 HBN for Al2O3. For tensile strength on composites with reinforcement particles through electroless coating of 190,27 MPa for SiC and 159,69 MPa for Al2O3 and for tensile strength on composites with reinforcement particles without electroless coating treatment at 189,63 MPa on SiC and 158,94 MPa on Al2O3.