The present invention discloses a transmission power control method and a user equipment. A power reference value adjusted is compared with a maximum transmission power of a channel in a narrowband mode, and a minimum value between the two is selected as the transmission power in the narrowband mode to avoid data from being transmitted by a higher power in the narrowband mode, so as to effectively reduce the interference to data transmission during coexistence of the narrowband mode and a wideband mode, improve the effectiveness of transmission power control in the narrowband mode, and prolong the standby time of the user equipment to the greatest extent.