In order to reduce the brittleness of high-strength gypsum, polyethylene fiber was used as toughening material, the effect of polyethylene fiber content on the property of high-strength gypsum was explored through compressive, flexural, uniaxial tensile and water absorption tests, the microscopic morphology of polyethylene fiber toughened high-strength gypsum was analyzed by SEM, and the mechanism of polyethylene fiber on the macroscopic property of high-strength gypsum was revealed. The results show that with the increase of polyethylene fiber content, the water absorption of high-strength gypsum increases, the compressive strength decreases, and the flexural strength and tensile properties show trend of decreasing first and then increasing. When the volume content of polyethylene fiber reaches 2.0%, the flexural strength and tensile properties are improved most obviously. Compared with the control group, the flexural strength of high-strength gypsum improves by 86.06%, the tensile strain increases by 4.45%, and the ultimate tensile stress increases by 102.78%. The incorporation of polyethylene fiber makes the high-strength gypsum exhibit excellent tensile strain hardening properties and the toughness is significantly improved. Based on the tensile test results, the tensile stress-strain curves of the polyethylene fiber toughened high-strength gypsum are regressed, and the tensile constitutive model is established, which can provide a reference for the property analysis of fiber toughened high-strength gypsum.