Aiming at the issue that the traditional OLSR protocol's multipoint relay selection mechanism relies solely on topological coverage while ignoring the dynamic quality of links, an improved OLSR scheme based on cross-layer design is proposed to optimize the MPR selection mechanism. A cross-layer comprehensive state factor is constructed, integrating multi-dimensional metrics such as the physical layer's bit error rate, the MAC layer's frame reception success rate, and the MAC layer's queue length. The HELLO message format is extended to include a new CSE cross-layer field, enabling real-time interaction of neighbor node states. A new MPR selection mechanism is designed, optimizing the traditional coverage-first strategy into a multi-objective decision-making model weighted by CSE. This mechanism employs a dynamic scoring function to simultaneously enhance link stability and load balancing. Simulation results demonstrate that CSE-OLSR outperforms the traditional OLSR in terms of packet delivery rate and average end-to-end delay, effectively improving the stability and reliability of data transmission, making it suitable for highly dynamic and high-load MANETs scenarios.