The invention relates to a VOC removal system for a polypropylene granular material, wherein the system comprises a roof type devolatilization tower with a weighing control system, a cyclone dust collector, a first-class heater and a second-class heater. A material inlet is arranged at the top of the roof type devolatilization tower, and a rotary discharging valve with a variable speed device is arranged at the bottom of the roof type devolatilization tower; the material inlet is connected with the cyclone dust collector; one side of the roof type devolatilization tower is successively provided with a first-class air inlet, a second-class air outlet and a cooling air inlet successively from top to bottom, and the other side is successively provided with a first-class air outlet, a second-class air inlet and a cooling air outlet successively from top to bottom; the first-class air inlets are connected with the second-class air outlets; the secondary air inlets are connected with the cooling air outlets; the material inlet in the roof type devolatilization tower is provided with a feeding uniform distributor; roof type drying pipes are distributed uniformly below the feeding uniformdistributor; the weighing control system is connected with the feeding uniform distributor and the variable speed device. The invention also discloses an application method of the system. The VOC removal system has the advantages of simple structure, less investment, high stability and good devolatilization effect.