Abstract: ‍ ‍For the low-latency demands of Internet of Things （IoT） communication and to ensure the flexibility of data transmission， the unmanned aerial vehicles （UAV） communication network based on short packet is proposed in this paper. Since the non-orthogonal multiple access （NOMA） technology can increase the number of served ground users， its application to UAV short packet communication （UAV-SPC） system can solve the problem of secure transmission for multi-user. Compared with orthogonal multiple access （OMA）， NOMA can effectively improve the channel access fairness and spectrum efficiency of the users， so it is widely used in downlink communication transmission. To solve the complex secure transmission problem under the constraints of power and decoding error rate， the existance of the optimal allocation of power， data transmission packet length and system transmission bits to maximize the average security throughput of target user is first proved. On this basis， the optimal solution of the secure transmission problem is obtained by the algorithm proposed in this paper. Experimental results validate the stability and feasibility of the algorithm. In addition， compared with the benchmark scheme， the proposed scheme can effectively reduce the communication delay of short packet transmission and improve the average security throughput of target users in the system.