Web-based educational systems are now becoming part of main stream education. As an essential component of the web based educational systems, the student model enables the system to provide individualised course contents and study guidance, and therefore to help the students with different backgrounds and knowledge levels to achieve their learning goals effectively on the web. A prototype student model was developed in this project for a web based learning system. The architecture of student model is divided in two parts: individual and group student models. The information contained in individual student model includes the student knowledge levels for course contents, study goals, learning styles, preferences, etc. The model is updated dynamically according to student study times and/or assessment results. The group student model is extracted by a cumulative analysis of the individual student models of various students and is used for giving guidance to the students. This study produced a unique two-fold web-based student modelling system that can be applied to intelligently deliver the courses for a wide range of subject domains.