Macro-defect-free(MDF) cement based materials is a new class of high-strength materials,but the poor water resistant performance cumber the area of its application.For this purpose,the alcohol-soluble phenolic resin precursor and high alumina cement were used in this study.Test results show that water only immerged the surface of MDF cement,so the flexural strength receded 6.8% in water in 1 year.