The invention relates to a fixing structure for a garbage separating device. A driving device comprises two groups of driving rollers arranged on a base according to a distributing form of four corners of a rectangle, wherein one group of driving rollers corresponds to the feeding end of a sieve body, the other group of driving rollers corresponds to the discharging end of the sieve body, and the sieve body is placed on the two groups of the driving rollers and is in tight contact with each driving rollers; a retaining device comprises a retaining seat corresponding to the discharging end of the sieve body and fixed together with the base, a retaining shaft fixed together with the retaining seat, and a retaining wheel movably connected to the retaining shaft, and the retaining wheel props the discharging end of the sieve body and synchronously rotates along with the sieve body. The rotating and the moving of the sieve body are simultaneously limited through the driving device and the retaining device, the sieve body is driven to rotate through mutual matching of the driving rollers and the friction strips of the sieve body, rubber rollers in the driving rollers support the sieve body, and vibration produced during the rotating process of the sieve body can be reduced. The retaining wheel is oppositely arranged in a discharging end positioned in an inclined low end, and the sieve body is propped through the retaining wheel, therefore, the sieve body is prevented from sliding during the work, and the work stability is ensured.