There is a control system for a hybrid vehicle including an internal combustion engine including a throttle valve on an intake air passage, and a generator coupled to an output shaft of the engine. The control system includes a controller. The controller is configured to detect shaft torque of the output shaft of the engine by the generator, calculate an actual value of a throttle flow rate based on the shaft torque, the flow rate being an amount of air that flows through the throttle valve, and learn flow rate characteristics indicating a relationship between a throttle opening being a degree of opening of the throttle valve and the throttle flow rate, based on an actual value of the throttle opening and the actual value of the throttle flow rate.