This paper makes qualitative analysis to the performance of soft handover technology of downlink WCDMA(Wideband code division multiple access) system,which will play an important role in the third generation mobile communication system.Taking handover margin as a criterion,it also gives a comparison between hard handover and soft handover.Moreover,the macro-diversity effect has been studied in detail.At the end of this paper,some equations are derived,in which two important parameters,i.e.,multipath characteristics and the user density in the cell,have close relation to the macro-diversity gain.