The cost of e-resource for library gradually increased every year. How to evaluate the using efficiency of e-resources had become one of the most important issues. This study applied Data Envelopment Analysis (DEA) method to evaluate the using efficiency of e-resources in the library. It included the efficient analysis, slack variable analysis, and sensitivity analysis of e-resource. This study took the database purchased by University A as the research target for empirical analysis. The results showed that DEA method could generalize the variables of each input and output based on the evaluated unit to calculate the maximum value of efficiency of each database then provide the comparisons and suggestions for improvement. The information provided by DEA was more diverse and objective than past evaluating methods.