The invention discloses an oral cavity diagnosis device. The device structurally comprises a device box, an output pipe, a detecting device, a cleaning box, a CPU processing unit and a PC circuit assembly, the output pipe is arranged at the bottom of the left side of the machine box, the end of the output pipe extends to the interior of the device box, a power line is arranged on the top of the output pipe, a supporting frame is arranged between the power line and the output pipe, the supporting frame is in threaded connection with the device box, the inspection device is arranged on the leftside of the power line, the inspection device is composed of a power supply device, and a handle, a micro motor, a transmission rod and an oral cavity mirror. According to the oral cavity diagnosis device, the spraying gun, the cleaning box, the micro motor and the transmission rod are arranged on the device, the device has diversified functions, the oral cavity condition of a patient is inspected, the oral cavity of the patient can be nursed and disinfected to provide convenience for a doctor to diagnose, the oral cavity mirror is extended into the oral cavity of the patient by the doctor, the angle of the oral cavity mirror can be automatically adjusted, psychological nervousness of the patient is not caused, and psychological pressure of the patient is relieved.