The space frequence multiplex technology in cellular network greatly relieves thecontradiction between the limited spectrum resource and rapid increase of subscribers. The capability ofCDMA cellular system is the largest

besides has the characteristic of soft-capability. Because of self-disturbed system

it is limited by the space Erlang capability when applying the Erlang B theorem. The article analyzed the method of calculating Erlang capability in CDMA system

finally some optimization work was involved about the characteritis of CDMA.