Marketing ethics of online enterprises is one of the important factors that impact the efficiency of the sybermarket. An appraisal model for marketing-ethics quality of online dealers is established by a questionnaire survey. Data shows that five factors determine the appraisal of online consumers to the online B2C dealers. They are the reliability of transaction, the security of transaction, the integrity of sale, fairness of competition and the appropriate of advertisement. The results provide online enterprises with empirical reference to improve their marketing ethics.