The advancements in hybrid and electric vehicles require an optimal utilization of the on-board energy sources to increase vehicle fuel economy, provide a safe and comfortable driving environment, and extend heating and cooling capacity range. Recently, the application of parallel propulsion technology to design and build hybrid vehicles has caused new concerns on climate control engineering. This study is the first to address the challenges on developing an innovative heating system for parallel hybrid vehicle applications.This paper presents a hybrid heating system for a parallel hybrid passenger car, in which a conventional coolant heater core loop and a heat pump loop are installed to meet the needs of cabin heating. Thermodynamic characteristics of various subsystems are discussed with respect to the variations of ambient temperature through the experimental and analytical comparisons. Furthermore, thermodynamic analysis is applied to evaluate the design and operating effectiveness of the hybrid heating system. To synthesize the operation of the heating system, a hybrid heating concept is proposed and applied to direct the optimal integration and identify the dynamic operating modes through a hypothetical drive simulation. The work reported in this paper is aimed at laying a theoretical and applied foundation to the development of automotive hybrid heating systems.