The processes of manufacturing FRP sewage disposal tanks are very dangerous and hazardous jobs for workers because of large size and heavy weight of the tank, toxic fiberglass dust, nasty smell, and dangerous tools such as hand-grinders. This paper introduces an automatic manufacturing system of the FRP sewage disposal tank to enhance the safety of workers. The system consists of 3 components: the FRP body rotation jig, the automatic manhole cutting machine, the automatic sanding processing machine. The safety of workers and working environment are greatly improved, because the dangerous jobs are automatized and the toxic fiberglass dust is automatically collected. Also, the productivity is greatly improved and the cost is reduced.