The invention provides a sludge-sand separation and dehydration integrated oily sludge and sand reducing device. According to the invention, a storage pool is connected with the liquid inlet of a cyclone separator through a pump and a pipeline; the top part of the cyclone separator is provided with a chemical addition opening which is connected with a chemical tank; the sludge outlet of the central part of the cyclone separator is connected with a sludge storage pool; the sand outlet of the bottom part of the cyclone separator is connected with a sand storage pool; the sludge pool is connectedwith a vibrating sieve; the liquid phase outlet of the vibrating sieve is connected with a dehydrator; the solid phase outlet of the vibrating sieve is connected with the sand storage pool; the solidphase outlet of the dehydrator is connected with the sand storage pool; the liquid phase outlet of the dehydrator refluxes to a storage pool; and the vibrating sieve and the dehydrator are fixedly arranged on a conveyor belt which is fixedly arranged above the sludge storage pool. The sludge-sand separation and dehydration integrated oily sludge and sand reducing device provided by the inventionhas the following advantages: particle sizes of sludge are effectively separated and controlled within the range of small particle sizes; the efficiency of reinjection can be effectively improved; andthe cost of reinjection is reduced.