The invention discloses a spray drying system for milk powder processing. A spray drying tower is connected with a cyclone separator, the spray drying tower is divided into two parts, namely a cylindrical part and a conical part, and milk powder on the inner wall is cleared by a ring-shaped sliding brush and a Y-shaped rotating brush; an exhaust fan is connected with an exhaust emission pipe of the spray drying system, a hot-air blower is connected with a hot air pipe, the exhaust fan and the hot-air blower are in the running state in the running process of the system, a feeding pump, a sprayer, a reduction gear I and a reduction gear II are controlled by a time relay to operate, the feeding pump and the sprayer run according to the running mode with running for 27 minutes and suspending for 3 minutes as a cycle, and the reduction gear I and the reduction gear II run according to the mode with running for 3 minutes and suspending for 27 minutes as a cycle. According to the spray drying system for milk powder processing, the ring-shaped powder clearing component and the Y-shaped rotating brush powder clearing component are arranged in the drying tower, a spraying device is provided with the running modes which are designed reasonably, the milk powder on the inner wall of the spray drying tower can be cleared away in time, and the milk powder quality and safety are guaranteed.