A transmission method, apparatus, and system based on uplink transmit diversity, relating to the field of communications are provided. To timely and efficiently determine to activate or deactivate uplink transmit diversity and improve uplink transmission quality, a base station sends an activation request instruction to a radio network controller when determining, according to relevant reference measurement value(s) of a user equipment, to activate uplink transmit diversity of the user equipment; and the radio network controller notifies, according to the activation request instruction, the user equipment of activating the uplink transmit diversity; or a base station sends a deactivation request instruction to a radio network controller when determining, according to relevant reference measurement value(s) of a user equipment, to deactivate uplink transmit diversity of the user equipment; and the radio network controller notifies, according to the deactivation request instruction, the user equipment of deactivating the uplink transmit diversity.