The description of iFLY system submitted for NIST 2008 speaker recognition evaluation (SRE), which has achieved excellent performance in the 2008 SRE evaluation, is presented in this paper. Our primary system is a fusion of two subsystems GMM-UBM and GMM-SVM. For each sub-system, two kinds of short-time acoustic features PLP and LPCC are adopted. We focus on three key issues in this evaluation: channel compensation, multi-lingual or bi-lingual cues and the voice activity detection. We also point out that data selection and factor analysis play key roles in the system improvement.