This paper is concerned with the design of a discrete-time linear parameter varying (LPV) regulator for a parallel hybrid electric vehicle (PHEV) based on an already exist optimal energy management strategy (EMS). The aim is to determine the regulating quantity of battery current and the power split ratio between engine and battery with respect to the achieved optimal ones by the exist optimal EMS, according to the driving cycle variation and battery capacity degradation. The system is modelled under linear fractional transformation (LFT) form with varying velocity and battery capacity represented as an uncertainty blocks. The discrete-time linear parameter varying (LPV) regulator which is scheduled by the varying parameters is synthesized using the approach proposed in [1]. The battery state of charge (SOC) estimation method based on the Kalman Filter and the battery capacity estimation method based on the Least Mean Square (LMS) are also given.