The invention relates to a vehicle-mounted instrument circuit structure for realizing immediate starting of a whole vehicle after micro power failure in an extremely low dark current dormant environment, the vehicle-mounted instrument circuit structure comprises an enabling input pin connected between a power supply chip and a storage battery power supply and used for controlling the enabling of the power supply chip through the storage battery power supply; and a diode connected between the storage battery power supply and the Vin power supply and is used for enabling the storage battery power supply to control the power supply chip through the unidirectional conduction of the diode. By the adoption of the vehicle-mounted instrument circuit structure capable of being started immediately after micro outage of the whole vehicle in the extremely-low dark current dormancy environment, a vehicle-mounted instrument is dormant when dark current is very small, a key is not rotated when a power source is restored after outage is conducted for 1-2 seconds, and a single-chip microcomputer is started by depending on reset of the instrument under the condition that message awakening is not sent. According to the invention, the enable input pin of the power supply chip is used, the output of the 5V power supply can be immediately closed as long as the enable input end is at a low level, andthe new problem that the instrument is immediately started after power failure and recovery under the condition of low dark current dormancy is solved.