A method and an apparatus for requesting system information, user equipment and a base station are disclosed by the present disclosure. The method includes: sending a first random access request, where the first random access request carries at least one pilot code for identifying to-be-requested SI; monitoring a response message corresponding to the first random access request within a preset time period, where the response message carries information for responding to the pilot code; and when the response message is detected, based on a pilot code identifier included in the response message, monitoring and receiving the to-be-requested SI within a transmission window of to-be-requested SI corresponding to the pilot code identifier. The technical solutions of the present disclosure can avoid a problem of long latency for the UE to obtain the SI, which is caused by the failure of the UE requesting the to-be-requested SI through the random access request so that the base station cannot broadcast the second type of SI in time.