A method and terminal for association update are provided. When the terminal performs location area update to a MSC/VLR via a GERAN/UTRAN, if it has performed combined update or CSFB attachment in an EPS network via E-UTRAN, then it sets a combined update indication which indicates the EPS network requires combined update when the terminal returns to the E-UTRAN from the GERAN/UTRAN; when the terminal moves to a registered tracking area of the E-UTRAN, it determines whether the combined update indication has been set or not, if yes, it initiates combined TAU and LAU to an MME. After receiving a location update request from the MME, the MSC/VLR updates stored association information and re-establishes SGs association with the MME. Accordingly, a terminal has a control module for association update, which comprises a combined update indication setting determination unit, a combined update setting unit and a combined update initiation determination unit. The present invention enables to update the SGs association in the MSC/VLR in time, thereby the MSC/VLR can always find UE through paging.