Abstract: MEP engineering has the characteristics of numerous specialties, diverse types of components and complex geometric relations, etc. And different types of components have different calculation rules, and some dedicated metering software has different degrees of restrictions in application, so the accurate calculation of the mechanical and electrical installation engineering quantity has always been the concern in the industry. Therefore, this article compares the similarities and differences between Revit software and the calculation rules in my country's Standard Method of Measurement for General Building Services Works (GB50856-2013). Adopting Revit plug-in development, the article reformulates the calculation rules by using C# computer programming language. The developed plug-in solves the problem of inaccurate quantities of components at some special-shaped fittings, and the interface is simple to operate. The quantities are exported in accordance with the specifications. Meanwhile the edited mapping table is matched with the bill attributes to the components one by one. Finally, the table of component detail and bill of quantities is summarized and exported. Through a practical engineering application, the engineering quantity derived is compared with the calculation results of the existing e-mechanical and electrical calculation plug-in in the market. The accuracy basically meets the requirements, and the rapid calculation under the 3D model is realized, which provides a new idea for improving the efficiency of the measurement and valuation of mechanical and electrical installation engineering.