The utility model relates to a power transmission mechanism capable of independently and automatically eliminating gaps. The power transmission mechanism comprises a motor 2, an intermediate shaft 5, and two output shafts 9 and 23. Power transmission is completed in such a manner that the motor 2 drives the intermediate shaft 5, two helical gears 33 and 34 on the intermediate shaft 5 drive two output shafts 9 and 23 through two sliding helical gears 16 and 24 on the output shafts, and then two output gears 11 and 22 on the output shafts 9 and 23 engage a tooth bar 32. The power transmission mechanism is characterized in that each of the two output shafts 9 and 23 is provided with a group of gap-eliminating spring mechanism. The power transmission mechanism is advantageous in that gaps or interference trend between two gears of the output shaft can be independently compensated by disk spring on respective output shaft pushing sliding gears. In this way, no extra rotation of the intermediate shaft occurs during the compensation process, and no extra irregular disturbance to the movement of a servo motor driving output shafts is generated, thereby ensuring the smoothness of power transmission and positioning accuracy of a workbench.