The invention discloses a method for optimizing iFC processing in IMS, which comprises the following steps: the invention increases mark ID on iFC of HSS, DSAI is explicitly connected with iFC throughiFC mark ID; and DSAI determines whether the correlation iFC is downloaded into S-CSCF or not; if DSAI is activated, the correlation iFC will be downloaded into S-CSCF, otherwise the correlation iFCcan not be downloaded into S-CSCF. AS modifies user service information and judges whether the corresponding iFC of AS of the user exists in local memory or not, if the iFC is not existed, the methodreads iFC corresponding to AS and correlation DSAI. AS device orderly judges whether every iFC relating to all service is activated or not, if yes, the DSAI value is activated, and if not, the DSAI value is not activated; and then the method judges whether reading DSAI value is in line with the DSAI value, if not in line with the DSAI value, then the method will modify the correlation DSAI value from HSS. The user registers S-CSCF and requests to download user data. HSS judges DSAI value relative to every iFC, if DSAI value is activated, the correlation iFC is downloaded to S-CSCF, and otherwise the correlation iFC can not be downloaded to S-CSCF. The invention overcomes defects of DSAI treatment in 3 GPP protocol. The explicit correlation between DSAI and iFC can improve the applicabilityof net unit application. The method reduces redundancy and improves operational efficiency.