Based on the development of forestry machinery and the causes for tractor accident, this paper analyzed the necessity of improving the small skidding tractors. Then the automatic overload alarm and automatic anti-tipping alarm were designed through the research on overload and tipping point of small skidding tractors. The main parameters of the devices were calculated, the operational principle was described and the two wiring diagrams were given. The feasibility of these two alarm devices is proved theoretically in this paper. Two ways are provided to improve the safety of logging operations of the tractor and an effective research method for its intelligent development in China is planed.