The drum type BB fertilizer mixer is an efficient mixing equipment specially used in the production of bulk blending (BB) fertilizers. It realizes the uniform mixing of various granular basic fertilizers (such as urea, phosphate fertilizer, potassium fertilizer and medium-trace element fertilizers) through a horizontally rotating drum. The equipment mainly consists of a cylindrical drum, transmission device, feed inlet, discharge outlet and control system. It utilizes the rotation of the drum to make materials roll and convect in the cylinder, achieving the effect of rapid and uniform mixing. It is suitable for small and medium-sized fertilizer processing plants and agricultural cooperatives. It can flexibly adjust formulas according to soil test results to produce targeted bulk blending fertilizers, widely used in large-scale planting of field crops and cash crops, meeting the needs of precision fertilization.