To promote the harmless treatment and resourceful use of steel slag, making steel slag into powder instead of quartz powder to prepare ecological ultra-high performance concrete (UHPC) is one of the effective ways to reuse it. To address the issue of the influences of raw material factors in the formulation of steel slag powder UHPC, the strength indicators of steel slag powder UHPC such as compressive strength, flexural strength, splitting tensile strength and elastic modulus were tested under different mix proportion using orthogonal test method, so as to analyze the effect of silica fume content, steel slag powder content, river sand content and steel fiber content on their various performance indicators. The test results show that the volume content of steel fiber has the most significant effect on the mechanical properties of steel slag powder UHPC, while the content of river sand and steel slag powder has a greater effect and the content of silica fume has a smaller effect. The order of significance in the indexes of cubic compressive strength, flexural strength and static compressive elasticity modulus is steel fiber>river sand>steel slag powder>silica fume. The order of significance in the indexes of axial compressive strength and splitting tensile strength is steel fiber>steel slag powder>river sand>silica fume. The optimum mix proportion scheme is obtained by orthogonal test, and the steel slag powder UHPC prepared according to this scheme has good working performance and mechanical properties.