The cow suffers were diagnosed from Hostein cows through determination of subclinicle mastitis diagnosing liquid and SCC (Somatic cell count), using “Ruyanning” provided by Yangling Lefure company in the experiment. Then 14 cows, which had similar ages, embryo times, childbirth time and day milk yield, were averagely distributed the test group and the control group. Moreover 7 cows from the other health cows, which had similar ages, embryo times, childbirth time and day milk yield, were made health group. After March 7, the test group were put the drug on the udders twice each day (in the morning and the evening), and the control group weren't put the drug. After a week, suffers were determined by BMT recessive mastitis, and surveyed SCC and milk composition. The result showed that SCC reduced significantly, and change rate was 67.3 percent (P<0.01), and that 79.8 percent recessive mastitis transform negative. Therefore, “Ruyanning” have significant treatment efficacy on recessive mastitis.