The disclosure claims a method and a device for determining a Radio Link Failure (RLF) reason, wherein a UE has an RLF in a first eNB where the UE is located, and successfully establishes a RRC with a second eNB. The method includes that: the UE sends RLF information to the first eNB, wherein the RLF information includes at least one of the following: the ambient signal quality information recorded by the UE when the RRC is established successfully, the location information of the UE when the RLF occurs, and the location information of the UE when the RRC is successfully established; the first eNB determines the RLF reason according to the RLF information. The disclosure solves the problem that the RLF reason cannot be judged accurately in the conventional art, and enables the network side to obtain more accurate and comprehensive information.