This application relates to the technical field of electronics, and discloses a detection circuit and a detection method of an electrical control device, and an electric vehicle. In some embodiments of this application, the detection circuit includes a drive circuit configured to detect an electrical control device. The drive circuit includes a drive power module and a low-side switch unit. The detection circuit includes: a first detection module, a second detection module, and a control module. The control module is configured to obtain an electrical signal at a third end of the first detection module, and/or an electrical signal at a second end of the second detection module; and determine, based on the electrical signal at the third end of the first detection module, and/or the electrical signal at the second end of the second detection module, whether the drive circuit of the electrical control device is faulty.