Disk aerator is also named aeration turnplate, belonging to horizontal hub disk type surface plug flow aerator in the mechanical aerator. The aerator is composed of an aeration turnplate, a horizontal shaft, bearings at two ends, a motor and a reducer. The turnplate surface is provided with trapezoidal lugs and round pits to increase air volume brought into mixed liquor and improve capability of cutting bubble and pushing mixed liquor. The installation density of the turnplates can be regulated to regulate the installation quantity of the turnplate on the machine set according to oxygen needing amount. Each turnplate can be independently disassembled for maintenance. The aeration turning disk is a core part of the disk aerator, directly related to the aeration efficiency of the aerator.