Abstract: The concentrator of floatation in Guixi smeltery have made an accident after put in to use, the concentrator is the main equipment in the mine, once have troubles with it, it will take long time to repair it and the cost is expensive. The main reason of this accident is that mechanical strength is not enough. There are not any protectors, in order to avoid the accident take place again, we design a protector and reduce the power of motor and improve the quality of cast, so it can prevent the parts destroying in overloading. The prong of concentrator can be auto raised and fallen according to the load. It is normal during 8 months.