The application of complex interventions in the area of public health, clinical research and education is becoming increasingly widespread. The effectiveness of complex interventions may be affected by numerous factors due to the complexity of interventions, intervention pathways or the context of implementation. Therefore, it is significantly important to evaluate the process of complex interventions, which will provide information to understand the implementation of interventions. The British Medical Research Council’s process evaluation guidelines provide a framework for implementing and reporting on process evaluation research. This paper aims to interpret the guide in detail on complex intervention and process evaluation for the references of domestic researchers.