The present invention discloses a method for improving the call success rate and a base station system thereof, which send reverse power control bits by using a specific parameter value according to the distance between a user and a base station, so as to improve the probability that the base station captures the mobile station and thereby improve the call success rate. The method includes the following steps of: distinguishing user type according to information in an origination message from a mobile station, and setting an initial value of a forward transmission power; and a base station sending a forward traffic channel null frame to the mobile station according to the initial value of the forward transmission power, wherein the forward traffic channel null frame contains reverse power control bits information.