In recent years, there has been a notable acceleration in constructing low-earth orbit (LEO) mega-constellations, which aim to provide users with worldwide high-capacity, low-latency communication services. However, the high-speed movement between satellite and ground nodes causes rapid changes in satellite-ground access relationships, which poses a significant challenge to the design of integrated space-ground addressing and routing. Furthermore, new services like direct cell phone connectivity are leading to an increasing number of ground users directly accessing satellite networks, exacerbating the abovementioned challenges. This paper introduces a flooding-free accurate addressing and routing solution for mega-LEO satellite networks (MARS), a cost-effective, easily convergent routing and addressing mechanism for mega-constellation networks. MARS encodes locations into addresses, conducts addressing using prior geographic information, and ensures 100% data reachability by employing distributed local synchronization of satellite-ground access relationships. Simulation results demonstrate the efficiency of MARS in terms of average hop count and load distribution.