Embodiments of the present invention provide a method and an apparatus for controlling transmit power of user equipment. The method includes: when total uplink transmit power of user equipment UE exceeds maximum allowed transmit power, calculating a first gain factor according to the maximum allowed transmit power; performing quantization processing on the first gain factor according to a gain factor of a first physical channel, to obtain a second gain factor, where the first physical channel includes a DPCCH2; reducing a gain factor of a second physical channel to the second gain factor, to reduce transmit power of the second physical channel, so that the total uplink transmit power of the UE does not exceed the maximum allowed transmit power, where the second physical channel includes an HS-DPCCH. This reduces a calculation error and improves control accuracy of transmit power.