A radio link (RL) parameter updating method of a high speed downlink packet access (HSDPA) system in a mobile communication system is disclosed. According to a radio channel situation of a terminal, an RL parameter applied to transmission and reception of control information between the terminal and a base station is dynamically controlled. For this purpose, the RL parameter updating method includes: a step in which the base station determines whether to update an HSDPA related parameter and transmits the parameter update information to the RNC to trigger updating of the RL parameter; and a step in which the RNC updates the HSDPA related parameter and transmits it to the terminal. The parameter update information is delivered through an RL parameter update response message, and the RNC is a serving RNC.