The invention provides an uplink system and a method and system for improving performance of the uplink system. A matching network is set up between a duplexer and a low noise amplifier, setting up parameters of the matching network are obtained through the following steps that impedance parameters and scattering network parameters of the duplexer and impedance parameters and scattering network parameters of the low noise amplifier are obtained respectively; target impedance parameters and target scattering network parameters of the matching network are calculated out according to the obtained parameters; a matching network model is set up, the matching network model is subjected to simulation, and when a simulation result of the matching network model accords with the target parameters, the setting up parameters of the matching network are exported according to the current matching network model. By means of the method and system, matching of the duplexer and the lower noise amplifier is achieved, it is guaranteed that the standing-wave ratio of an input port of the uplink system meets the system requirement, and low noise coefficient of the system is achieved. The obtaining method of the setting up parameters of the matching network is simple and easy to realize, and high precision is guaranteed.