The invention relates to an outlet temperature control optimizing method of a medium-speed coal pulverizer of a thermal power generating unit. The method is characterized in that a PID (Proportion Integration Differentiation) adjuster is additionally arranged in control logic configuration of a DCS (Distributed Control System) of the thermal power generating unit, and linkage control logic is added to the control logic configuration of the DCS of the thermal power generating unit; a primary air pressure setting value correction control loop port based on the outlet temperature control optimization of the medium-speed coal pulverizer is added to primary air pressure control loop configuration of the control logic of the DCS of the thermal power generating unit, and primary air pressure setting value correction linkage control logic output is introduced to the primary air pressure setting value correction control loop port based on the outlet temperature control optimization of the medium-speed coal pulverizer to be used as the primary air pressure control correction; and the DCS is put into actual operation, and the parameters of each control loop in the outlet temperature control of the medium-speed coal pulverizer of the thermal power generating unit are adjusted online, so as to achieve the expected effect. The method is high in real-time performance, simple in on-site debugging process, and conveniently carried out in engineering.