Abstract: The effect of closure pressure, time, etc. on the long-term conductivity of propping fractures was studied by FCES-100 and the experimental results show that closure pressure and time are main factors affecting the conductivity of haydite with a certain radius. The function expression of the conductivity changing with the closure pressure and time was regressed by statistical principle on the basis of a lot of experimental data, and its accuracy was tested through practical application. The result is useful to scientific research and fracturing on spot. Furthermore, it is a new attempt to calculate the long-term conductivity of propping fractures.