In the building of smart city, mobile Ad hoc network (MANET) has shown tremendous application potential because of its flexibility, distributivity, on-demand and selforganization. High-speed mobility and heavy-load traffic in MANET may lead to the existence of frequently interrupted flows and prematurely drained energy, which degrades the performance of routing protocols. In this paper, a novel routing algorithm called as power controlled and stability-based routing protocol (PCSR) is proposed, aiming to improve the energy efficiency and route stability. In PCSR, a local connectivity table is firstly constructed at MAC layer without extra control packets, which is utilized to decide stable forwarding path at network layer. In addition, for the purpose of saving energy, the power for transmitting both control packets and datagrams is reduced in PCSR. Extensive simulations demonstrate that compared with existing routing protocols, our proposed PCSR consumes less energy and prolongs network lifetime with guaranteed packet delivery.