In the existing Dual LAN （Local Area Network） Terahertz Wireless LAN （Dual-LAN THz WLAN） related MAC （Medium Access Control） protocol， some nodes may repeatedly send the same Channel Time Request （CTRq） frame within multiple superframes to apply for time slot resources and idle time slots exist in some periods of network operation， therefore an efficient MAC protocol based on spontaneous data transmission SDTE-MAC （high-Efficiency MAC Protocol based on Spontaneous Data Transmission） was proposed. SDTE-MAC protocol enabled each node to maintain one or more time unit linked lists to synchronize with the rest of the nodes in the network running time， so as to know where each node started sending data frames at the channel idle time slot. The protocol optimized the traditional channel slot allocation and channel remaining slot reallocation processes， improved network throughput and channel slot utilization， reduced data delay， and could further improve the performance of Dual-LAN THz WLAN. The simulation results showed that when the network saturates， compared with the new N-CTAP （Normal Channel Time Allocation Period） slot resource allocation mechanism and adaptive shortening superframe period mechanism in the AHT-MAC （Adaptive High Throughout multi-pan MAC protocol）， the MAC layer throughput of the SDTE-MAC protocol was increased by 9.2%， the channel slot utilization was increased by 10.9%， and the data delay was reduced by 22.2%.