This article examines the criterion system of evaluating computer network information retrieval tools, and supplies techniques and procedure of evaluating performance of those tools by means of statistics.

Some uses of the powerful retrieval tool from the viewpoint of scientific researcher and worker are also illustrated with practical examples.

This paper selected the paper quantity which is chosen in "The Chinese Journal Square Matrix",is embodied by the important indexing tools at home and abroad and 3 items of document measuring target as the evaluation factors to expand the evaluation formula.

The key to construction and utilization of the databank is; firstly, the management of bibliographical information resources; secondly, the unification of bibliography indexing tools; thirdly, the management of the cataloging system.

This paper has provided several retrieval tools in agricultural sciences for agricultural research workers:retrieval periodicals,sci-tech report,retrieval tools published both China and abroad,that are of high practical value.

The problems and the possible solutions of Internet searching enginean do the retrieval tools are discussed.

Net search tools emerged as the times require.