In view of the requirements of torque-based engine control and coordinated control for hybrid powertrain systems during mode switching and shifting, engine torque needs to be known. A framework for torque generated model was established, and the influencing factors of engine effective torque were analyzed. Then steady and transient performance tests of DEUTZ 6V1015 diesel engine were designed in order to get sample data to train ENNs. By use of the trained ENNs the estimations of both steady and transient friction torque and indicated thermal efficiency were completed, results were: the estimation error of friction torque and indicated thermal efficiency was less than 5%. Then the complete torque generated model was established by embedding the trained ENNs, and the estimation of effective torque was done, results were: the estimation error was less than 5%. These lay the foundation for realizing torque-based engine control and coordinated control of engine and electric motor of hybrid powertrain system in mode switching and shifting processes. Then the time-varying characteristic of engine was taken into account, and speed closed-loop correction was introduced based on the open-loop torque generated model, which have significantly improved the robustness of the model.