In the EPC general contracting mode, the general contractor is responsible for the entire construction project, but it does not mean that the general contractor must personally complete the entire construction project. Except for the work that is explicitly required by law to be completed by the general contractor, the general contractor may adopt professional subcontracting for other work. In practice, general contractors often subcontract equipment procurement (manufacturing), construction, and installation work to professional subcontractors based on their rich project management experience, different scales, types, and owner requirements of engineering projects. Therefore, in the EPC general contracting mode, the contract structure is usually manifested in the following forms:
（1） Turnkey general contracting;
（2） Design Procurement General Contracting (E-P);
（3） Procurement Construction General Contracting (P-C);
（4） Design Construction General Contracting (D-B);