The present disclosure provides a method of reporting radio link failure information, a method of obtaining radio link failure information, a terminal, and a network side device. The method of reporting radio link failure information, applied to a terminal, includes: recording radio link failure (RLF) information, in a process of the terminal performing a radio resource control (RRC) connection re-establishment or a RRC connection establishment, the RLF information including at least one of: a tracking area code (TAC), a tracking area identifier (TAI) and a system identifier of a terminal access cell, wherein the RLF information is related to a time of RRC connection establishment or RRC connection re-establishment; reporting the RLF information to a network side device.