With the introduction and application of big data, the power companies have entered the era of big data. In this paper, we make a study of electric power engineering supervision mechanism based on big data from four areas of cost, quality, schedule and safety. We have clever integration of the original project supervision approach and power big data, changing the way of doing supervision, by building two databases ： transverse database and longitudinal database, namely： the same project database and historical project database. During the course of project supervision, we collect the real – time data of this project and extract useful information of the vertical and horizontal databases. Then, we compare real – time data with databases to identify problems and take remedial measures timely. The fusion of big data and power project supervision is becoming a trend, which could achieve it roundly and timely. It is also an optimal choice for project supervi- sion by now.