IEEE 802.11ax is the emerging standard release of the next-generation of wireless local area networks (WLANs). The core idea is to enhance the area throughput in high-density deployment scenarios through high efficiency (HE) multiple access control (MAC) and physical layer (PHY) technology. Orthogonal frequency-division multiple access (OFDMA) technology has been selected as the key techniques in 802.11ax. However, the existing OFDMA technology has an interference diffusion problem, i.e., multi-user parallel transmission aggravates the interference to the surrounding cells. To solve these problems, we propose a spatial clustering group-based OFDMA protocol (SCG-OFDMA). In the SCG-OFDMA protocol, the concurrent transmission of nodes with close spatial distance can reduce the degree of interference diffusion. Particularly, the SCG-OFDMA protocol and process are designed based on the 802.11ax Multi-User (MU) MAC framework. The computer simulation analysis results demonstrate an improvement in the throughput of 36.62% at most.