In order to evaluate the strain YJ 085# with weak flocculation ability, carbohydrate inhibition experiment were established for identification of its flocculation phenotype.Gene expression analysis through real time PCR (qPCR) was carried out to reveal the transcription level during fermentation process.Sugar experiment revealed that the phenotype of YJ085# was New FLO.RNA extraction and gene expression showed that levels of FLO family gene were significant low compared with control.FLO10 was "silenced".Expression of FLO1 and FLO11 remained low during the fermentation process.Gene FlO5 and Lg-FLO1 were the dominate genes which affects flocculation ability.Compared to the control strain, the flocculation performance of strain 085# was decreased by 63.98%, which revealed the molecular foundation of weak flocculation ability of YJ085#.