Low-power Wide-Area Network (LPWAN), as a wireless connection technology of the Internet of things, has met the requirements of power consumption of network providers and operators, network coverage and Internet of things equipment. As the main technology of LPWAN, Long Range (LoRa) has entered the stage of scale deployment. However, in the MAC protocol of LoRa, multiple end nodes send data to the gateway at the same time, which will cause serious collision problems. When data collision occurs, the gateway will no longer receive collision data, and the data packet needs to be retransmitted after a certain time. In order to solve this problem and improve the throughput of the whole system, this paper proposes to introduce the sparse code multiple access (SCMA) technology of 5G non-orthogonal multiple access (NOMA) into Long Range Wide Area Network (LoRaWAN) architecture from the perspective of code domain. The theory and simulation results show that SCMA can effectively solve the problem of data collision and improve the system throughput.