Provided is a vehicle generator control method. An engine ECU controls the generator according to an operating condition of the engine, and the control process is as follows: when the engine ECU determines that the engine is in a starting condition, the engine ECU controls a generator separately excited loop to be disconnected, so that the generator does not generate electricity; and when the engine ECU determines that the engine enters an idling condition, the engine ECU controls the generator separately excited loop to be closed, so that the generator is started to generate electricity, and after the generator is started to generate electricity, the generator carries out normal electricity generation until the engine stops operating. Through the vehicle generator control method, the starting load of the engine can be effectively reduced, and cold starting capacity is improved. Also provided is a vehicle generator control system.