In this research, the mechanical, thermal and water absorption properties of low-density polyethylene (LDPE) as matrix material. The white kaolin (WK) powder weight content in the consistent particle size (150 μm) and different weight ratios (5, 10, 20, and 30) wt.% and the chemical composition of WK were investigated by atomic absorption spectrum and x-ray diffraction. The mechanical tests such as tensile strength, modulus of elasticity, and elongation at break%, and test of water absorption were applied on the prepared samples. The obtained results showed that the addition 5-20% of white kaolin powder to LDPE led to increasing the tensile strength, modulus of elasticity, and a decrease of % elongation at break, Water absorption was reduced by increasing of white kaolin contents from 5-20%. However, the higher amount 30% of WK were increased.