The invention provides a clothes washing and clothes drying all-in-one machine and a control method thereof. The clothes washing and clothes drying all-in-one machine comprises a shell, a first drum assembly used for drying clothes, a second drum assembly used for washing the clothes and a drainage pipe, the first drum assembly used for drying clothes and the second drum assembly used for washing clothes, the first drum assembly and the second drum assembly are arranged in the shell separately and can run independently, the first drum assembly is internally provided with a first cavity, and the second drum assembly is internally provided with a second cavity; the drainage pipe is used for draining washing water and is communicated with the second cavity; a direct drainage drying mode is adopted by the first drum assembly, and a wet and hot air outlet of the first drum assembly is communicated with the drainage pipe. By making the wet and hot air outlet of the first drum assembly communicated with the drainage pipe, wet and hot air of the first drum assembly is directly drained by the drainage pipe of the second drum assembly, the purpose is achieved that the wet and hot air for drying the clothes and the washing water for washing the clothes are directly drained by the same drainage assembly, the overall structure is simplified, and a user more conveniently utilizes the clothes washing and clothes drying all-in-one machine.