Abstract: A large amount of industrial solid waste phosphogypsum has caused serious pollution to the environment. At the same time, the contradiction between the traditional cement industry with high energy consumption and the realization of the "double carbon" target has become increasingly prominent. Some studies have shown that the cementitious material based on phosphogypsum can replace part of ordinary Portland cement, but its working and mechanical properties are poor when using raw materials without treatment. In this paper, the green and high strength phosphogypsum based cementitious materials were prepared by using common industrial solid wastes such as original phosphogypsum, slag, steel slag and limestone. The results show that chelates are formed by mixing 0.5wt% plant protein with Ca²⁺ in the gelling system to produce a coordination compound covering the surface of gypsum nucleus, which not only delays the setting time of the gelling material, promotes the hydration reaction degree, but also improves its mechanical properties. The microstructure and composition analysis show that phosphogypsum is mainly used as a filler in the cementitious material, the slag is activated by the alkali of steel slag, and the limestone promotes the hydration reaction while providing Ca²⁺. Based on the original solid waste phosphogypsum, using the mixture ratio of m_{phosphogypsum}∶m_slag∶m_{steel slag}∶m_limestone = 0.45∶0.35∶0.1∶0.1, 28 days flexural strength of mortar specimen is 7.0 MPa, compressive strength is 39.1 MPa, and softening coefficient is 0.91, which is very close to the performance of P·O 42.5 grade ordinary Portland cement.