Firstly, the triangular whitenization weight function which corresponds to class 1 is changed to a whitenization weight function of lower measure, and the triangular whitenization weight function which corresponds to class s is changed to a whitenization weight function of upper measure. The puzzle of extending the bound of value of each clustering index is avoided due to this betterment. A novel two stages decision model with grey synthetic measure is proposed for the problem that it is difficult to determine the ascription of decision object at the case of each ponderance with equilibrium value of the grey clustering coefficient vector delta_i  or the case of some front main ponderances with close value of the grey clustering coefficient vector delta_i . Finally, two practical examples are presented to verify the effectiveness of the proposed model.