The present application relates to the technical field of wireless communications, and in particular to a method for determining an establishment reason, and a terminal, for solving the problem, existing in the prior art, that there is no solution for determining an establishment reason yet under a 5G NR system. In the embodiments of the present application, an RRC layer of a terminal determines an access category of the terminal, and determines, according to a mapping relationship between the access category and a connection establishment reason, a connection establishment reason corresponding to the access category for the terminal. Since a RRC layer of a terminal in the embodiments of the present application determines, according to a mapping relationship between an access category and a connection establishment reason, a connection establishment reason corresponding to the access category for the terminal, a solution for determining an establishment reason under a 5G NR system is provided.