In this paper，the core of condition attributes with respect to decision attributes in rough sets theory is used for selection of attributes in multivariate tests．A new concept of generalization of one equivalence relation with respect to another one is introduced and used for construction of multivariate tests．The comparison between multi-variate decision tree and univariate decision tree is done through an example．The results show that the former is more simple than the latter．The basic comparison among several multivariate decision trees iS fulfilled．