Based on the network traffic flow data, this study will analyze the network user's behaviors. Currently, most of the traffic analysis reports are mainly based on the Cisco Netflow data only, which will categorize a lot of services belonging to 'others'. Therefore, we use a different approach and design software to collect data. Our approach, combining Netflow data and packet-sniffing, will reduce the percentage of 'others'. TamKang University campus network environment is our study case. Our study has the following findings: most of the network bandwidth is used by P2P software to transfer the files, approximately 34%. Among the P2P software, the largest service item is the eDonkey, approximately 24%. Most of the traffic in each group is used by only a few users. The behaviors of the broadband users are significantly different than the narrowband users. To download the files is the major purpose of the broadband users, but the narrowband users are used to get their Emails. The files with the video files extensions of dat、mpg、avi and with image file extensions of iso、mdf、img are the primary file types transferred by campus users.