To develop a location system for small agricultural machines in the Chinese south, a laser emitting and tracking system based on double laser-emitter and three-point location was designed based on the laser three-point theory. The theory of double-laser-emitter and three-point location was introduced; then, the laser emitting and tracking system was designed, including the designs of working mechanism and controlling circuit for the laser emitter. The Kalman filtering algorithm based on a incremental PID with quick correction functions was proposed to estimate the moving targets in laser tracking and to compensate the errors in changing speeds and turning corner of the machine. A series experiments were performed. The experiment results show that the targets of laser receiver can be tracked dynamically by both laser emitters in real-time, and the maximum deviation is ±2.8 cm, which meets the location requirement of an autotracked-driving farming machine for an accuracy of ±4 cm within 200 m. For the reliable and effective algorithm, it can lay a foundation for unmanned driving of farmland machines and data collection in farming fields.