The traditional grey clustering model based on the real numbers is extended to the condition in which the observation values and the turning points of the whitenization weight function are the interval grey numbers. By representing the interval grey number based on “kernel” and degree of greyness, and using the “unreduced axiom of degree of greyness” as the theory basis, the expression of whitenization weight function with interval grey number is given, and the interval grey number operation is transformed into real number operation, then the grey fixed weight clustering model is established. Finally, the interval grey clustering model is used to evaluate the core competencies of high tech enterprises in Jiangning District of Nanjing. The result shows that the model is effective and reasonable.