Traditional initial support construction has characteristics of low safety, high labor intensity, serious environmental pollution and difficult quality control. In order to improve the existing working environment and improve the construction quality and progress, a horseshoe prefabricated initial support structure is proposed. The structural design scheme, prefabrication method, assembly method and test examples were introduced in detail, and the key technologies were described. The results show that: in the block design of steel reinforced concrete structure, all factors such as stress state, loading mode and structural lifting shall be taken into account, at the same time, the processing difficulty of section steel shall be considered, the bending radius of single section steel shall not exceed 2. Flexible formwork and rigid back ridge are effectively combined, which can prefabricate all kinds of special-shaped structures, and the materials can also be reused with good economy. The cracks of the prefabricated initial support structure begin to develop when the design load is 2.3 times, and the connection joint failure occurs when the design load is 3.1 times. The test shows that its bearing capacity meets the engineering requirements.