The invention relates to a diatomite reactor device. An outer shell (1) of the device is composed of an upper octagonal column body and a lower octagonal cone body, eight supporting columns (2) are arranged on the eight corners of the outer side of the octagonal column body for supporting, gutters (9) are horizontally formed in the inner side of the upper octagonal column body of the outer shell (1) along the circumference, at least four stand columns (4) are arranged on slopes of the lower octagonal cone body of the outer shell (1), hollow cylinders (5) are fixedly connected to the top ends of the stand columns (4), the internal area defined by the stand columns (4) and the hollow cylinders (5) is a flocculation chamber (6), the external area defined by the stand columns (4) and the hollow cylinders (5) is a clarifying chamber (7), an ultrafiltration layer (20) is arranged in the clarifying chamber (7), a unit weir groove net (8) is arranged on the top of the clarifying chamber (7), a gradually-expanding guide cylinder (10) is arranged in the flocculation chamber (6), the bottom of the gradually-expanding guide cylinder (10) is connected with a water inlet pipe (11) which is connected with a pipeline mounted pump (12), sludge buckets (13) are arranged on the middle-lower portions of the slopes of the clarifying chamber (7), sludge discharging pipes (14) are connected in the sludge buckets (13), and the sludge discharging pipes (14) are connected to a sludge storage pool, and a return pipe (15) is arranged at the inner bottom of the device and connected to a biochemical pool anoxic zone. The diatomite reactor device is simple in structure, good in sewage processing effect, small in occupied space, low in investment and attractive and elegant in appearance.