A power control method based on Downlink Piloting Time Slot, DwPTS, comprising an open-loop power control procedure while a terminal is getting accessed randomly and a closed-loop power control procedure while communications are being maintained after the terminal is accessed, wherein the said open-loop power control procedure while a terminal is getting accessed randomly further comprises: A. the terminal measuring the received DwPTS signal powers transmitted by adjacent base stations during cell searching, sorting the base stations in the order of signal intensity of DwPTS, and determining candidate base stations; B. the terminal calculating the Uplink Piloting Time Slot, UpPTS, transmission power for open-loop power control while the terminal is getting accessed according to the base station transmission power broadcast by the most suitable candidate base station, the expected receiving power and the DwPTS signal power of the base station actually measured by the terminal, and sending an access request to the most suitable candidate base station with this transmission power; and the said closed-loop power control procedure after the terminal is accessed further comprises: C. the base station determining the required receiving power, determining actual uplink transmission power required by the base station for closed-loop power control, sending the required receiving power to the terminal, and sending the actual uplink transmission power required by the base station to the terminal with a closed-loop power control command; D. the terminal keeping measuring the actually received DwPTS signal power of the base station, then calculating an uplink transmission power reference value for open-loop power control according to the base station transmission power and the required receiving power; and E. comparing the calculated uplink transmission power reference value under open-loop power control with the actual uplink transmission power required by the base station under closed-loop control and obtaining a difference, comparing the difference with a threshold; if the difference is larger than the threshold, the terminal performing uplink transmission with the power which is equal to the sum of the calculated uplink transmission power reference value for open-loop power control and the threshold (360, 370), if the difference is not larger than the threshold, the terminal continuing to execute the closed-loop power control command and performing uplink power transmission with the actual transmission power required by the base station for closed-loop power control. A. the terminal measuring the received DwPTS signal powers transmitted by adjacent base stations during cell searching, sorting the base stations in the order of signal intensity of DwPTS, and determining candidate base stations; B. the terminal calculating the Uplink Piloting Time Slot, UpPTS, transmission power for open-loop power control while the terminal is getting accessed according to the base station transmission power broadcast by the most suitable candidate base station, the expected receiving power and the DwPTS signal power of the base station actually measured by the terminal, and sending an access request to the most suitable candidate base station with this transmission power; and the said closed-loop power control procedure after the terminal is accessed further comprises: C. the base station determining the required receiving power, determining actual uplink transmission power required by the base station for closed-loop power control, sending the required receiving power to the terminal, and sending the actual uplink transmission power required by the base station to the terminal with a closed-loop power control command; D. the terminal keeping measuring the actually received DwPTS signal power of the base station, then calculating an uplink transmission power reference value for open-loop power control according to the base station transmission power and the required receiving power; and E. comparing the calculated uplink transmission power reference value under open-loop power control with the actual uplink transmission power required by the base station under closed-loop control and obtaining a difference, comparing the difference with a threshold; if the difference is larger than the threshold, the terminal performing uplink transmission with the power which is equal to the sum of the calculated uplink transmission power reference value for open-loop power control and the threshold (360, 370), if the difference is not larger than the threshold, the terminal continuing to execute the closed-loop power control command and performing uplink power transmission with the actual transmission power required by the base station for closed-loop power control.