The invention discloses a multi-pool parallel-connection temperature-increasing heat-preserving high-temperature fermentation large-middle-sized biogas digester. The multi-pool parallel-connection temperature-increasing heat-preserving high-temperature fermentation large-middle-sized biogas digester consists of a plurality of fermentation pool bodies, a lighting transparent plate, a connecting support, a material liquid mixing pool, a stirrer, a feeding pump, a feeding pipe, a discharging valve, a discharging pipe and an air guide pipe, wherein each fermentation pool body is a metal pool body which is formed by welding steel plates and coated with black anticorrosive paint, the periphery of the pool body is connected with a lighting transparent plate combined vacuum layer in a sealing manner, so that the pool body achieves an optimum effect for increasing the temperature and preserving the heat, the size of the pool body lined at the end of the plurality of the fermentation pool bodies is half of the size of the previous fermentation pool bodies, material liquid in the rear pool is completely discharged out of the pool body after being thoroughly fermented, the feeding pump is started to feed new material into the previous fermentation pool from the material liquid mixing pool by virtue of the feeding pipe, the discharging pipe valve of the front pool is opened, the material liquid automatically flows into the rear fermentation pool by virtue of the water level difference, finally the small fermentation pool is full, feeding of the front fermentation pool is stopped. The multi-pool parallel-connection temperature-increasing heat-preserving high-temperature fermentation large-middle-sized biogas digester has the beneficial effects that high-temperature fermentation is realized, the biogas yield is high, energy conservation and environment protection are realized, the operation cost is low, the material liquid is thoroughly fermented, and the slag liquid discharged from the rear pool is free from bacteria and viruses, free from secondary pollution and capable of being directly made into high-quality environment-friendly organic composite fertilizer.