It is of great important to study the cercospora leaf spot resistance of sugar beet M14 which has No. 9 chromosome of Beta corolliflora Zoss in addition. After spraying with the Cercospora beticola Sacc. conidia suspension, enzyme activities in leaves of suger beet M14 and Beta vulgaris L. were experimented, then the amino acid contents in leaves were also analyzed .The results showed that all of the enzyme activities detected in leaves of sugar beet M14 were higher than those in Beta vulgaris L., and the total content of amino acid in suger beet M14 decreased quickly after infected, while it increased in Beta vulgaris L..Therefore, we can conclude that it is valuable to study sugar beet M14, which has moderate resistance to cercospora leaf spot.