Abstract: Dynamic inspection is a significant work in the process of gas field exploitation. Contraposing the slow rapidity of closed-in pressure comeback, overtime of pore pressure test, great workload and high cost when carry through repeated off-take potential in low permeability gas field, on the basis of theory of gas reservoir engineering, the research concludes the simple method of calculation of present pore pressure, open flow potential and the position of well bore fluid level. It not only reduces the workload of dynamic inspection, but also can offset or remedy the dynamic inspection data, which is absent or unsuccessful. At the same time, it provides the new method to research the theory of gas reservoir engineering, and it has instructional function. The calculation practice indicates the application is simple and the result is reliable.