As a new generation wireless communication standard, 802.11be has achieved significant improvement in data transmission volume and efficiency, but it still has deficiencies in deterministic transmission, which cannot meet the new service requirements. Therefore, this paper proposes a deterministic transmission method (OTRS) based on the combination of OFDMA and rTWT. The OTRS transmission architecture is designed to increase the service grouping of the rTWT beacon frame interval period, and the rTWT time-domain resource scheduling algorithm based on the service grouping is proposed to effectively reduce the terminal transmission delay jitter and satisfy the deterministic transmission requirements. Considering the existence of delay jitter caused by throughput imbalance, the throughput optimization transmission model is established, and the delay jitter elimination algorithm based on throughput balanced scheduling is proposed to reduce the delay jitter and further ensure the demand of deterministic transmission. Simulation results demonstrate that the method proposed in this paper exhibits excellent deterministic transmission performance in terminal-dense transmission scenarios.