Abstract: In order to better prevent the low critical value gas dynamic phenomenon causing a danger to the mine safety production, with the statistic analysis on th e gas content, gas pressure and gas pressure gradient under the gas geological conditions in the three soft coal field of Yuxi Area, in combination with the analysis proo f method of the comprehensive energy presupposition, a study was conducted on the dynamic phenomenon of the low critical value gas.The results showed that when t he seam was soft and the coal ruggedness coefficient was low, the seam with low gas content and low gas pressure also would be easy to occur the gas dynamic phen omenon.