The invention discloses a combined washing and drying machine, which comprises a main frame. A washing machine is installed in a lower frame of the main fame. A drying machine is installed in an upper frame of the main frame. An electrical control board is connected to the upper portion of the washing machine through a second isolation layer. The upper portion of the electrical control board is connected with the drying machine through a first isolation layer. The washing machine is provided with a washing machine operating door. The drying machine is provided with a drying machine operating door. The combined washing and drying machine combines the existing washing machine and the existing drying machine, so that manufacturing materials can be saved, and manufacturing cost can be reduced. The combined washing and drying machine in a combined structure is small in occupied area during use. The drying machine is at an operating height above, thereby being convenient to use.