This study examines the effect of addition rice starch particle (RSP) in Polyethylene terephthalate (PET) based blend composites. The concentration of RSP in PET was varied at 0, 5, 10, 15 and 20 wt% with fixed percentage of sorbitol for 2 ml. The blend composites were produced by solution mixing method. All samples were tested by tensile and morphological observation after tensile test. The tensile test proves that the addition of RSP in PET increased tensile strength of blend composites. The maximum tensile strength was in 15 wt% RSP in PET for 9.79 MPa. Optical microscope displays minimum porosity with good fusion between RSP and PET. The addition of starch in polymer is suggested to reduce the percentage of using non-biodegradable polymer plastic. This research is important due to the development of biodegradable polymer.