This paper develops an energy control strategy based on a multi-parametric programming control algorithm for a parallel hybrid heavy-duty truck. First, based on the non-linear characteristics and multiple working modes of the heavy-duty truck, a set of piecewise linear models including longitudinal dynamics, engine and electric motor are established and synthesised to a mixed logical dynamic (MLD) model. Then, an objective function for achieving the best fuel economy is formulated and the optimal control law is analytically calculated using a multi-parametric programming algorithm. Finally, the simulation of the hybrid heavy-duty truck model is conducted under UDDSHDV drive cycle and the result shows that the multi-parametric programming energy control strategy can effectively improve fuel economy compared to the traditional heavy-duty truck simulation model with the same engine.