This paper proposes a Maximizing Duty-Cycle network lifetime (MDCLCR) Cooperative Routing algorithm to address the issues of short network lifetime and high maintenance costs in wireless sensor networks (WSNs) within smart communities, which are caused by high-density deployment and heterogeneous energy constraints. By integrating cooperative communication and duty-cycle techniques, the MDCLCR algorithm dynamically optimizes routing paths based on the Dijkstra framework. It combines cooperative node selection strategies and adaptive transmission mode selection strategies to jointly perceive channel states (attenuation due to building blockage), initial node energy (differences in micro-battery capacity), and dynamic residual energy, thereby achieving balanced energy consumption and alleviating hotspot problems. Experiments show that in a simulated smart community with a dense 50-node network, compared to the flow-augmenting cooperative routing algorithm (FACR), the MDCLCR algorithm extends the network lifetime by 30% to 14%. Although cooperative transmission increases average energy consumption by 16% compared to the classic cooperative algorithm (CAN), it extends the maintenance-free period of devices and reduces the frequency of community manual inspections.