System and method for controlling engine revolutions for hybrid construction machine

A system and method for controlling engine revolutions for a hybrid construction machine is provided. The system for controlling engine revolutions for a hybrid construction machine, including an engine (10), a hydraulic pump (13) which is driven by the engine (10) to drive a hydraulic actuator (15) with discharged hydraulic fluid, a motor-generator (17) which is driven by the engine (10) to generate electricity and to drive the hydraulic pump (13) as a motor supplementing the engine (10), an energy storage device (19) which is charged with electric energy generated by the motor-generator (17) and which supplies the electric energy for motor operation of the motor-generator (17), a torque detection means (40) for detecting an output torque of the hydraulic pump (13) that is required to drive the hydraulic actuator (15), and a hybrid control means (50) for controlling the motor operation of the motor-generator (17) so as to supplement the engine output if the change of the output torque of the hydraulic pump (13) detected by the torque detection means (40) exceeds a predetermined level and it is determined that an engine revolution drop will occur.