In sugar production, dextrans are undesirable compounds synthesized by contaminant microorganisms from sucrose, increasing the viscosity of the flow and reducing industrial recovery, bringing about significant losses. In this article a laboratory investigation have been done on the concentration of dextran in kenana sugar factory deteriorated cane and sugar industry products, as well as their effects on the sugar factory operation. In addition, the effective concentration of biocides (Busan and formaldehyde) as inhibitor to bacteria responsible for formation of dextran has been done. Because of the spectrum of molecular weight of dextran the Robert and Polarization methods were used for juices and Haze method for quality of sugar. The results obtained by Robert method were the average concentration of dextran in crusher; mixed, clarified and limed juices are 603,358, 289,and 424 ppm respectively. Also the results obtained by polarization method show that the average concentration of dextran in crusher juice from filed (burned cane) was lower than dextran in crusher juice from factory. The results obtained by Haze for A- and B- raw sugar 56 and 86 ppm respectively. It was found that the high viscosity of dextran affected the rate of flocculation. It was noticed that pure juices had turbidity of 14.17; an addition of 1.6g dextran in 100ml of juice elevated the turbidity to 17.7nm, besides increase reading of Pol and Brix. It was found when 1 ml of Busan diluted 34 times with water while 1 ml of formaldehyde diluted 4 times , 0.05 ml from each was added to I ml of crusher juice both proved to be effective to inhibit the growth of bacteria. Accordingly comparing the biocides (Busan and Formaldehyde), it was found that the Busanis clearly more effective than Formaldehyde.