The utility model discloses a brush cutter, including the mobile jib, the one end of mobile jib is provided with the saw bit base through fastening bolt, the below of saw bit base is provided with thesaw bit fixed block through fixing bolt, the both sides of saw bit fixed block all are provided with saw bit screens board through fixing bolt, the below of saw bit fixed block is provided with the saw bit, the opposite side of mobile jib is provided with servo motor through fastening bolt, one side of servo motor is provided with the braces, one side of braces is provided with first handrail, one side of first handrail is provided with second handrail fixed baseplate, through the hollow retaining device in inside of design, avoided external force to lead to the fact the problem of damage tothe saw bit, inside the saw bit lies in the baffle, external force can not touch the saw bit, only can touch the baffle, and the effectual saw bit of having protected makes the saw bit not receive thedamage, has increased the life of saw bit, has practiced thrift the cost, has also eliminated the potential safety hazard simultaneously.