The invention provides an automatic humidification control method and automatic humidification control system of a fuel cell. The automatic humidification control method comprises the steps of acquiring a target positive electrode circulation pump rotational speed, a target negative electrode circulation pump rotational speed, target positive electrode tail exhaust valve openness and target negative electrode tail exhaust valve openness according to an output load current, humidity deviation quantity and press deviation quantity; and inputting the target positive electrode circulation pump rotational speed, the target negative electrode circulation pump rotational speed, the target positive electrode tail exhaust valve openness and the target negative electrode tail exhaust valve opennessinto a fuel cell system. Therefore, accurate control and rapid response of humidity and pressure of a proton exchange membrane fuel cell can be achieved under the condition of no external humidifier by the automatic humidification control method of the fuel cell; and meanwhile, by the automatic humidification control method of the fuel cell, the structure of the fuel cell system can be simplified,and the flexible adjustment of the humidity and the pressure of the fuel cell under different working conditions is met.