Recently, flying Ad Hoc networks (FANETs) have been widely applied to various civil and military applications. Medium access control (MAC) protocols have attracted much attention due to its impact on the overall network performance. However, due to the unique characteristics of FANETs applied in military such as multi-priority differentiation requirements, high mobility and dynamic topology, traditional MAC protocols cannot meet the requirements of FANETs. Tactical targeting network technology (TTNT) proposes statistical priority-based multiple access (SPMA) that can support multiple service prioritization and provide extremely low access latency for high priority services. Therefore, the design and optimization for SPMA protocol has become a new research focus. This paper firstly compares SPMA protocol with carrier sense multiple access (CSMA) protocol, and introduces the working mechanism of SPMA protocol. Subsequently, the optimization of SPMA protocol is discussed and qualitatively compared from the perspectives of implementation methods, advantages and limitations. In the end, the issues and research challenges are summarized and discussed.