Engine control system and method for hybrid vehicle

1. Field of the Invention An engine control system for hybrid vehicles, so as to smoothly switch the driving operation from the cylinder-deactivated engine operation, in which at least a part of the total number of cylinders of the engine is deactivated, to the all-cylinder-activated engine operation while considering the driver's intention. When the vehicle is decelerated, the cylinder-deactivated engine operation is performed and regeneration using the motor is performed. The system includes a cylinder deactivation release determining section for releasing the cylinder-deactivated engine operation when an engine speed decreases to a reference engine speed with respect to the cylinder-deactivated engine operation; and a brake operation detecting section for detecting whether a brake pedal is depressed. The cylinder deactivation release determining section includes a cylinder deactivation condition changing section for changing the reference engine speed according to whether the brake pedal is depressed, which is detected by the brake operation detecting section.