Narrow Band Internet of Things(NB-IoT), as a low-power wide area network technology, is specially designed to connect a large number of low-power devices . The low-orbitsatellite IoT based on this technology has lower transmission loss and delay , and can achieve seamless coverage of the earth through constellations . However, low-orbit satellites are highly dynamic and face QoS requirements from different users . These factors greatly affect the throughput performance of existing resource scheduling algorithms . In response to these challenges, this paper proposes a high-throughput NB-IoT low-orbit satellite IoT resource scheduling algorithm by comprehensively considering satellite channel characteristics , reliability and delay requirements between different users, and differential Doppler caused by high satellitedynamics in a scenario where a large number of IoT users request wireless resources and timefrequency resources are limited. Simulation results show that compared with existing methods , the resource scheduling algorithm proposed in this paper shows significant performance improvement in system throughput.