Explosive characteristics of polybasic explosive mixture gas are systematically re-searched. Over 28000 experimental data have been obtained from 1278 effective experiments. The paper probes into the concentration explosive limits and the container factors of polybasic explosive mixture gas which contains H2, CH4 and CO. It has worked out the sufficient and necessary condi-tion for branch-chain explosion and the unified expression of the probability of the heterogeneous chain termination. Experiments indicate that the concentration explosive limits of polybasic explo-sive mixture gas(H2, CH4, CO) relate to many factors. They enlarge with the augmentability of the container(linear size, geometric shape, and flame spread direction). This will be of great significan-ce to guiding the revision of related industrial safety targets, reclaiming and reusing related indus-trial tail gas and waste gas, taking precautions against the explosion hazard of mixture gas in cor-related industry and mines, and applying the branch chain burning and branch chain explosion into practice.