A method and system for improving robustness of context update messages in robust header compression are disclosed in the present document, wherein, the method includes: when sending the context update message, a compressor performing check processing on important fields in the context update message, generating a check code, and sending the check code and the context update message out together; and after receiving the context update message and the check code of the important fields in the context update message, a decompressor firstly performing checking on the important fields in the context update message, if the checking is passed, continuing to execute decompression processing, and if the checking is failed, discarding the context update message. With the present document, the probability of mistaking other compression packets for IR/IR-DYN messages due to bit errors of packet format fields can be reduced, and the correctness of packet format identification can be improved.