In order to solve the problems of class 3 permissible explosive for rock roadway excavation in coalmine, such as low explosion energy, short footage and low utilization rate of blast hole, through a large number of laboratory test and plant test, a new explosive composition, the high power class 3 coal mine water gel explosive to improve blasting power was developed, and detected by the authority department. Results show that after 6 months storage, detonation velocity of new explosive is 3600 m·s^-1, power 239 mL, toxic gas composition 20 L·kg^-1, which is better than class 2 coal mine water gel explosive. And its fuel gas safety, sensitiveness, anti-deflagration reach standard of class 3 coal mine water gel explosive. On-site rock roadway test was carried out for study the validation of explosive blasting power from the parameters including the footage, utilization rate of blast hole, hole depth, waste rock fragmentation, thrown distance, around forming and explosive consumption. Results show that under the same conditions and blasting material consumption, the rock breakage capability of new high power class 3 coal mine water gel explosive is near that of the class 2 coal mine water gel explosive, higher than that of class 3 coal mine water gel explosive.