A dendritic polymer, a dendritic polymer monomer, and a hyperbranched copolymer are described. The dendritic polymer monomer has a structure denoted by Z′-(Q)n-Y, wherein Z′ represents a structure denoted by the following formula (a) and/or formula (b), Q represents a dendritic constitutional repeating unit of the dendritic polymer monomer, n represents the generation number of the dendritic polymer monomer, and is an integer within a range of 2-6, Y represents a group that contains SO3− or COO−, R14-R16 can be identical to or different from each other, and are H or C1-C5 alkyl respectively. The monomer can be used as a copolymerizable monomer for preparing a hyperbranched polymer applicable to oil fields, the obtained hyperbranched polymer can be used as an inhibiting filtrate reducer for drilling fluid, flocculating agent, encapsulating agent, heat-resistant and salinity-resistant polymer flooding agent, and thickening agent for fracturing liquid, etc.