Embodiments provide an access method and device. The method includes: sending, by a user terminal, a carrier extension request to a base station when a current service resource demand is greater than a specified threshold, where the carrier extension request is used to request the base station to allocate an available spectrum resource; receiving the available spectrum resource sent by the base station. The method also includes obtaining through calculation, according to the current service resource demand and the available spectrum resource, a quantity of antenna channels that need to be enabled, and enabling an antenna channel corresponding to the quantity of antenna channels. The method also includes sending an access request to the base station, where the access request carries the antenna channel that is to be enabled by the user terminal.