Abstract: In IEEE 802.11ax system， the large number of stations and the potential high packet collision rate lead to a significant reduction in the communication efficiency of WLAN. This paper proposes a multi-user scheduling and resource allocation algorithm based on transmission delay to solve the problem of invalid frame filling in uplink multi-user transmission. Based on dynamic transmission time of frame interaction scheme in uplink scheduling access， access point （AP） combined with the channel state information （CSI） and buffer state report information （BSR） provided by the station （STA） to determine the transmission delay of each station. Aiming to minimize the transmission delay difference of users within the group， the user grouping strategy and resource unit （RU）-STA matching scheme were proposed. Then， aiming to maximize transmission efficiency， the transmission power of each user is determined and the channel utilization rate of each group is guaranteed. Compared with the reference scheduling strategy， the proposed algorithm improves the channel utilization rate of continuous multi-frame transmission by 10% to 15%， and also ensures the stability of the user network throughput.