The structure of grinding and mixing machine was studied for the security perspective. The production limit experiment was carried out. Plugging material conditions and the detonation velocity of explosive were observed via adjusting operation parameters: feeding speed, scraper angle, grinding and mixing machine speed. The safety of the grinding and mixing machine was analyzed and discussed. Results show that when the speed of the grinding and mixing machine is 22.8 r·min^-1, the feeding speed 4 t·h^-1, the scraper angle 24°.