The invention discloses a rice transplanter steering automatic control system and belongs to the technical field of agricultural machinery control. The rice transplanter steering automatic control system is characterized by comprising a vehicle-mounted computer (1), a signal conditioning module A (2), a display module (3), a wireless transmission module (4), a storage module (5), a signal conditioning module B (6), a GPS positioning device (7), a vehicle speed sensor (8), a microcontroller (9), a signal conditioning module C (10), an alarming module (11), a driving module (12), a power supply module (13), a signal conditioning module D (14), a position and attitude sensor (15), an angle sensor (16), a steering motor (17), a speed reduction module (18), a hydraulic steering booster (19) and steering wheels (20). Compared with the prior art, the rice transplanter steering automatic control system has the advantages of being simple in system structure, convenient to mount, debug and maintain, high in system reliability and measurement precision, low in power consumption, easy to popularize and the like.