The purpose of this study was to determine how is the effect of Marketing Information System on Competitive Advantage simultaneously or partially and to knowing what dominant variable to Competitive Advantage in SME's Ornamental Flowers in Batu City. The type of research in this study is explanatory research which uses a questionnaire research instruments that distributed to 125 respondent that is the chiefs and members of SME's Ornamental Flowers in Batu City. As for the data analysis using descriptive analysis statistics and Inferensial analysis statistics in the form of multiple linear regression. The results showed that from three variables Internal Record, Marketing Intelligence and Market Research simultaneously affecting Competitive Advantage. From the SPSS 13.0 calculation for significance test simultaneously generates a value of F = 35,544 with a probability of 0,000 < 0,05. Partially, Marketing Intelligence known to negatively affect the Competitive Advantage, while Internal Records and Market Research have significant effect on Competitive Advantage. In addition to F test, R2 test shown that the value of R2 is 0,455 which means that the amount of independent variables on the dependent variable is 45,5%.