The utility model relates to a multi-grid vertical flow granular sludge cultivating device used in treatment of municipal sewage and industrial wastewater and aims at solving the technical problems of lower biomass, low treatment efficiency, fewer microbial populations and poor removal of nitrogen and phosphorus pollutants in the sewage in the prior art. The multi-grid vertical flow granular sludge cultivating device comprises a pool body, a sewage inlet pipe, a water inlet groove, a water outlet pipe, a water outlet groove and a sludge discharge pipe, wherein a plurality of pairs of vertical diversion plates are arranged in the pool body for dividing the pool body into a plurality of spaces connected in series; in each pair of the vertical diversion plates from the water inlet end to the water outlet end, a spacing interval is arranged between the bottom end of the first vertical diversion plate and the bottom of the pool body, and the bottom end of the second vertical diversion plate is closed and fixed at the bottom of the pool body so as to divide the spaces into a water flow down channel and a water flow up channel; a plurality of layers of reticular partition plates are erected in the water flow up channel in a horizontal way; and an air pipe and an aerator are arranged at the lower part of the water flow up channel, the air pipe and the aerator are connected with the air pipe. The multi-grid vertical flow granular sludge cultivating device is very conductive to removing the nitrogen and phosphorus pollutants in the sewage and can improve the biological oxidation effect by 5-10% and the construction cost can be reduced by 5%.