Abstract: On the basis of the comprehensive analysis of the five factors (4M1E) in the impact of construction quality of Building Engineering, with deep research on the Man factor in the important role of 4M1E, the paper reached a conclusion that the Man factor is the primary factor influencing the construction quality, and put forward the countermeasures to control the Man factor effectively. In the process of construction supervising of engineering project, the supervisors should put the control of the Man factor as the key factor for controlling 4M1E. Facts prove that, seizing the Man factor as the key with pre-controlling it comprehensively in the process of construction, the effective control of construction quality can be achieved.

Key words: 4M1E, the primary factor, quality control, countermeasures