The invention discloses a horizontal plane motion mechanism for a towing tank test, which comprises a plane motion mechanism comprising a transverse oscillation frame 8, a transverse oscillation motion component 9, a yawing oscillation motion component 10, a transverse beam 6, a front connecting rod 5, a front connecting rod 11, adjusting rods 4 and 12, joints 3 and 13, force balances 2 and 14, and the like. The upper part of the horizontal plane motion mechanism is connected with a tank trailer 7 through the transverse oscillation frame 8, while the lower part is connected with a ship model 1 through the connecting rods 5 and 11 and force balances 2 and 14. By adopting a rolling guide rail, the transverse oscillation motion component has the characteristics of long service life, free maintenance for long-term work, high speed, low noise, high capacity of absorbing a mounting dimension error, and the like; and the transverse oscillation amplitude is over +/-1m, the ball screw precision is high and a transverse oscillation amplitude error is less than 0.2mm. Due to the adoption of a self-lubricating bearing and worm gear transmission, the yawing oscillation motion component has the advantages of wide rotation angle range, high torque, high self-locking property and high precision. A plurality of groups of connecting rod mounting holes are formed on the transverse beam and are suitable for different ship models. The connecting rod is provided with a linear bearing, and when the ship model is influenced by an external force to oscillate up and down, the connecting rod automatically adjusts the length, can remove a force in the vertical direction, and improves the accuracy of the maneuvering performance test. The control system is driven by a servo motor, a photoelectric encoder is used for sampling and feeding back, and a PLC programmable logic controller is used for controlling. The horizontal plane motion mechanism has the advantages of convenient control.