Provided are a busbar assembly and a cylindrical power battery module. The busbar assembly is used for electrical connection of a cylindrical power battery module. The cylindrical power battery module includes an input copper bar, an output cooper bar and a cells contact system assembly having the corresponding number as submodules. The input copper bar is connected to a cell unit at an input terminal of the cylindrical power battery module, the output copper bar is connected to a cell unit at an output terminal of the cylindrical power battery module, and the cells contact system assemblies are connected in series and in parallel to cell units of the submodules.