Now, peoples are interested in analyzing log files which can offer valuable insight into web site usage. The log files shows actual usage of web site under all circumstances and don’t need to conduct external experimental labs to get this information. This paper describes the effective and complete preprocessing of access stream before actual mining process can be performed. The log file collected from different sources undergoes different preprocessing phases to make actionable data source. It will help to automatic discovery of meaningful pattern and relationships from access stream of user.