A channel estimation method, a base station, user equipment (UE), and a system are provided. The method includes: setting up, by a base station, a connection to user equipment UE; and sending, to the UE, notification information indicating that the UE is in a radio remote scenario, where the notification information is used to instruct the UE to perform channel estimation by using a channel estimation algorithm applicable to the radio remote scenario, and the channel estimation algorithm is used to perform channel estimation on a signal that is obtained after downlink signals from multiple radio remote units RRUs are superposed. The UE can perform channel estimation by using the appropriate channel estimation algorithm, to effectively improve accuracy of the channel estimation, thereby effectively improving a downlink data throughput of the UE.