The traffic on WWW is increasing at a rapid rate due to users interaction with web sites, these activities contributes to enormous information which is maintained in Web log file. Web usage mining plays an important role in discovering frequent pattern from Web data, that helps to better serve the need of Web based applications. In present research work, researcher finds out different user and their session, which help in identifying unique user's navigational path from preprocessed Web log data. Further, researcher also proposed Modified Apriori algorithm which helps in extracting frequent usage pattern using average support.