The invention provides a section design method and device for an irrigation and drainage dual-purpose channel, and equipment. The section design method for the irrigation and drainage dual-purpose channel comprises the following steps that: S10: calculating the drainage ability of the channel so as to judge whether the drainage requirements of the irrigation and drainage dual-purpose channel are met or not; S20: when the channel can not meet the drainage requirements of the irrigation and drainage dual-purpose channel, regulating the channel bottom elevation and the design water level of the channel to enable the channel to meet the drainage requirements of the irrigation and drainage dual-purpose channel; and S30: on the basis of the regulated channel bottom elevation, designing the section dimension of the irrigation and drainage dual-purpose channel to enable the flow and the water level of the channel to meet the irrigation requirements. According to the section design method, which is disclosed by the embodiment of the invention, for the irrigation and drainage dual-purpose channel, the existing channel is transformed into the irrigation and drainage dual-purpose channel, andthe section of the irrigation and drainage dual-purpose channel is designed in a transformation process so as to guarantee the irrigation requirements of an irrigation area to a maximum degree in a most economical way.