Abstract: In this research, we cloned and sequenced 2 genes[SAV-940（aveC）and SAV-4584（wblA）]which may closely relate to Avermectin production, in both Avermectin overproduction strain Streptomyces avermitilis AV-326 and the initial strain Streptomyces avermitilis AV-95 which the overproduction strain resulted from. In addition, Real-time quantitative PCR was applied to detect the relative expression levels of the 2 genes, at 4 time points（36 h, 48 h, 120 h and 240 h, respectively）in the fermentation process. Results showed that amino acids sequencees respectively coded by the 2 genes were exactly the same in both two strains；but expression levels of gene aveC were obviously higher in the high performance strain than in the initial one at all four tested time points, while those of gene wblA were remarkably higher in the initial strain during Avermectin synthesis period.