The invention discloses a programming voltage generation circuit and an automobile diagnostic system. The programming voltage generation circuit comprises a programming voltage output end connected with multiple chips and a power output module connected with the programming voltage output end and outputting the first programming voltage to the programming voltage output end. The programming voltage generation circuit further comprises a first controller connected with the chips and a voltage adjustment module connected with the first controller and the power output module. The first controller is used for outputting a corresponding first control signal according to the preset programming voltage of one chip to be programmed in the chips. The voltage adjustment module is used for adjusting the first programming voltage output by the power output module to be the same as the preset programming voltage according to the first control signal. Through program control, the output programming voltage can be continuously adjusted, and the programming voltage generation circuit has the beneficial effect of being easy to operate.