Terahertz (THz) wireless personal area networks (T-WPANs) operate in the terahertz band, which has greater signal attenuation especially when the air is rich in water molecules, so it’s essential to consider the signal attenuation characteristics of the wireless link in terahertz wireless communication. In this paper, we focus on the poor link condition in T-WPANs, and a improved high throughput and low delay MAC protocol (IHTLD-MAC) for T-WPANs is proposed. By the on-demand retransmission mechanism based on verification, reserved time slots mechanism based on channel condition and the dynamic acknowledgement mechanism adaptively, IHTLD-MAC can allocate the slots resource reasonably, improve the network throughput and reduce the data latency. The simulation results show that IHTLD-MAC has better network performance compared with the existing IEEE 802.15.3c and the ES-MAC in bad link condition.