A technology for reducing and recycling treatment of sludge of a sewage treatment plant comprises steps as follows: sewage is treated with an air-floatation method, pretreated sewage and primary sludge are produced, the pretreated sewage is drained after biochemical treatment, treatment by a secondary sedimentation tank and disinfection treatment, excess sludge is separated in the secondary sedimentation tank, the primary sludge and the excess sludge are concentrated, and concentrated sludge and a supernate are separated out; the concentrated sludge has an anaerobic digestion reaction, digested sludge is subjected to incineration or landfill treatment after dehydration and drying treatment, a filtrate is produced during dehydration of the digested sludge, and biogas is subjected to power generation and/or heat recovery treatment after dehydration and desulfurization treatment; the supernate and the filtrate are mixed for nitrogen and phosphorus removal. With the adoption of the technology, the primary sedimentation effect of the sewage is improved, the yield of the primary sludge is increased, the primary sludge is removed before biochemical treatment, the yield of the excess sludge is decreased from the source, the primary sludge and the excess sludge are subjected to anaerobic digestion treatment, the higher organic matter transformation rate and the higher biogas yield can be obtained, and the sludge can be reduced and recycled.