Abstract: ‍ ‍Unmanned Aerial Vehicle （UAV） ad-hoc networks feature dynamic topology， self-organization， and multi-hop routing. The Media Access Control （MAC） protocol outlines how nodes can efficiently transmit data while utilizing limited channel resources. It is an important technology for satisfying data transmission quality of service requirements， and its performance directly determines the operational efficiency of UAV ad-hoc networks. Design optimization of protocols is critical to enhancing the stability and reliability of UAV ad-hoc networks. Compared with other classical MAC protocols， the Statistical Priority-Based Multiple Access （SPMA） protocol uses mechanisms such as multi-priority access， channel detection， and flow control. Therefore， it can better meet the requirements of UAV ad-hoc networks with low latency， differentiated services， and large-scale connectivity. However， this protocol faces the problem of increased packet collisions in the case of high bursts and high loads of network traffic. Therefore， this paper introduces a new threshold-setting method and probabilistic access control for low-priority data. In the case of high network traffic， the proposed method decides whether to delay or deny access to the service based on the comparison results of the new threshold value and periodic load statistics. Meanwhile， the access control of different low-priority data was conducted by calculating their transmission probabilities. Simulation results verify that the proposed method can maintain a more stable throughput of UAV ad-hoc networks and support better differentiated Quality of Service （QoS） requirements for different types of services， compared to the existing SPMA protocol. However， there are still some shortcomings， and future research can consider the following aspects： 1） Priority threshold setting strategy in multi-hop scenarios. The current threshold studies are all proposed based on all-pass network scenarios， and dynamically adjusting the priority thresholds in multi-hop scenarios can improve the data transmission performance. 2） Considering external interference and topology changes， adjusting the access strategy of the protocols according to the environmental changes， and more fully utilizing the prioritized channel resources.