LoRaWAN， as a wireless communication standard in Low Power Wide Area Network （LPWAN）， provides the support for the development of IoT （Internet of Things）. However， limited by the characteristics of incomplete orthogonality among Spreading Factor （SF） and the fact that LoRaWAN does not have a Listen-Before-Transmit （LBT） mechanism， the ALOHA-based transmission scheduling method will trigger serious channel conflicts， which reduces the scalability of LoRa （Long Range Radio） networks greatly. Therefore， in order to improve the scalability of LoRa network， Non-Persistent Carrier Sense Multiple Access （NP-CSMA） mechanism was proposed to replace the medium access control mechanism of ALOHA in LoRaWAN. The time of accessing the channel for each node with the same SF in LoRa network was coordinated by LBT， and multiple SF signals were transmitted in parallel for the transmission between different SFs， thus reducing the interference of same SF and avoiding inter-SF interference in the common channel. To analyze the impact of NP-CSMA on the scalability of LoRa networks， LoRa networks constructed by Lo RaWAN and NP-CSMA were compared by theoretical analysis and NS3 simulation. Experimental results show that NP-CSMA has 58.09% higher theoretical Packet Delivery Rate （PDR） performance than LoRaWAN under the same conditions， at a network communication load rate of 1. In terms of channel utilization， NP-CSMA increases the saturated channel utilization by 214.9% and accommodates 60.0% more nodes compared to LoRaWAN. In addition， the average latency of NP-CSMA is also shorter than that of the confirmed LoRaWAN at a network traffic load rate of less than 1.7， and the additional energy consumption to maintain the CAD （Channel Activity Detection） mode is 1.0 mJ to 1.3 mJ and 2.5 mJ to 5.1 mJ lower than the additional energy consumption required by LoRaWAN to receive confirmation messages from the gateway when spreading factor is 7 and 10. The above fully reflects that NP-CSMA can improve LoRa network scalability effectively.