Considering the influence of speed on the path tracking accuracy of transplanter, a path tracking algorithm based on speed self-adjusting is proposed to the improve performance of the linear path tracking of transplanter operating in complex field environments. Firstly, a speed self- adjusting fuzzy controller is established, where the lateral and heading deviations are taken as inputs and driving speed as outputs. Then the look- ahead distance is adjusted online through the adjusted driving speed, and the desired front-wheel turning angle is obtained using a pure pursuit algorithm in combination with the look-ahead distance adaptive strategy. A simulation experiment based on Matlab/Simulink and a field experiment were carried out to verify the performance of the proposed algorithm. The Kubota SPU-68C rice transplanter with the automatic navigation control system was used as a test platform in the field experiment. The results showed that the proposed algorithm could automatically adjust the driving speed of the transplanter according to the real-time deviation. Compared with the pure tracking algorithm, the proposed algorithm can obtain better path tracking accuracy and achieve the linear tracking state faster.