In this work, we study the stabilization of a pendulum system by coupling with a heat equation through the left boundary observation of the heat equation, while a velocity feedback of the pendulum system is designed to affect the same side heat flux of the heat equation. Based on the semigroup approach and Riesz basis method, the well-posedness and exponential stability of the system is deduced. Finally, some numerical simulations are presented to show the effectiveness of this feedback control design.