A side key assembly of a mobile terminal, and a mobile terminal. The side key assembly comprises: a side key and a fixed support frame that is used to be fixed in a housing of a mobile terminal. The fixed support frame is provided with a through hole fitted over the side key. The sidewall of the through hole is provided with at least one elastic pressing piece. When the side key passes through the through hole, the elastic pressing piece presses against the sidewall of the side key. According to the technical solution above, the position of a side key is limited by an elastic pressing piece provided on a fixed support frame, so as to reduce shaking that occurs when the side key is assembled on a mobile terminal. Furthermore, the position of the side key is limited in advance by means of the fixed support frame, to prevent a flexible circuit board connected to the side key from being scraped, thereby facilitating assembling the side key on the mobile terminal, and improveing assembly efficiency of the mobile t
