There are kinds of nutrients including Vc in citrus juice. But naringin and limonin, the main bitter substances which are difficult to be accepted during drinking and thus limit the citrus further processing, were also found. The characteristic of limonin biodegradation in citrus juice by lactic acid bacteria was studied. A strain of streptococcus lactis had the maximum percentage of limonin biodegradation rate among the tested lactic acid bacteria. The limonin biodegradation rate of 667% was obtained when the strain of streptococcus lactis was cultivated under the optimum conditions of the temperature of juice at 37℃, the original pH of juice, the loading volume of 150 mL juice in 250 mL flask and stationary culture. It was also showed that treatment with lactic acid bacteria had much decrease in the concentrations of limonin and naringin, a little increase in the contents of the soluble solids and the Bx of sugar and little impairment of quality parameters of citrus juice, including pH value and titratable acidity. 