Recycled high density polyethylene (HOPEr) has low strength and needs to be improved. Calcium carbonate (CaCO3) was used to reduce shrinkage and increased dimensional stability of recycled high density polyethylene (HOPEr). Stearic acid treatment was used to increase interaction and dispersity of calcium carbonate to recycled high density polyethylene. Stearic acid treatment for calcium carbonate was used to increase the tensile properties of HOPEr/CaCO3 composite. In this study, stearic acid treatment of CaCO3 was carried out by wet treatment method and 4wt% concentration of stearic acid. Then, the HOPE(r)/CaCO3 composites was extruded to form 3O printer filament. FTIR showed stearic layer on CaCO3 as a results of wet treatment. SEM morphology showed decreased agglomeration and increased dispersity of CaCO3. This is due to increase compatibility and interface interaction of CaCO3 and HOPE(r).Treated CaCO3 decreased the shrinkage of HOPE(r)/CaCO3 composites. Treated CaCO3 showed higher tensile properties of HOPE(r)/CaCO3 composites.