The invention discloses a multi-group driving type mechanical force saver, which includes a support, wherein a driving shaft and a driven shaft positioned in the same horizontal line and being parallel to each other are rotationally installed on the support respectively; four horizontal guide rail groups parallelly distributed are fixed on the support; a first 90-degree driving gear, a second 90-degree driving gear, a third 90-degree driving gear and a fourth 90-degree driving gear arranged at intervals, all forming 90 degrees in the circumferential direction and being equal in the radius R are fixedly installed on the driving shaft respectively; and a first driving arm, a second driving arm, a third driving arm and a fourth driving arm are equal in length (L equals to Pi* R/2), and are arranged at intervals and form 90 degrees in the circumferential direction of the driven shaft. According to the invention, front and rear half gear sections of the four groups of 90-degree driving gears apply work sequentially and alternately during the 45-degree rotary stroke of the driven shaft, so that the driven shaft can obtain useful power during the 360-degree rotation.