An integrated pressure control actuator assembly of a hydrogen supply system includes: a start/stop solenoid valve, a bypass valve, and a pressure control actuator, which are integrally formed in a single body; a normal flow path formed on the body, through which hydrogen gas is transferred from the start/stop solenoid valve to the pressure control actuator; an auxiliary flow path formed on the body, through which hydrogen gas is transferred according to opening and closing of the bypass valve connected to the normal flow path; and a control means for controlling the opening and closing of the bypass valve by detecting a failure of the pressure control actuator. The assembly enables the fuel cell vehicle to be driven in a limp home mode in the event of an emergency by adjustment of the pressure of hydrogen.