A simulation model of the current rotary drilling rig (RDR) system was built according to the basic configuration of the TR160D-type rotary drilling rig, and the test-rig based on the working principle of the RDR system was built. The results show that simulation model of the RDR system was accurate and reasonable by means of comparative analysis between theoretical computation and test data. The working principle and logic threshold control method of the HDR system were presented to reduce the fuel consumption and improve energy-saving efficiency via the analysis of energy flow of the RDR system, which mainly includes engine, electric motor/generator, super capacitor, AC-DC rectifier/DC-AC inverter and torque coupler, etc. Finally, the comparative analysis of the fuel economy between the RDR and the hybrid drilling rig (HDR) system was completed in the same overall typical operating conditions. The results show that energy-saving efficiency of HDR system is at 18.8% and total fuel economy efficiency of HDR reaches 15.9% relatively in a typical operating condition. (C) 2015 ISTVS. Published by Elsevier Ltd. All rights reserved.