In order to solve the problems of high computational complexity and a large amount of computation in Z-number multiple criterion decisionmaking, a simple and effective multicriterion decisionmaking method based on granularity is proposed.The linguistic Znumber decision information is transformed into the classical fuzzy number,and the proposed likelihood degree formula is used to compare the pros and cons of the scheme in pairs,the weight of each criterion is calculated according to the defined fuzzy degree formula, and then the final decision matrix is obtained. Finally, based on the basic theory of quotient space, the QUALIFLEX sorting method is improved, according to the falsity preserving principle and the degree of dominance between schemes,the optimal solution of the problem can be determined in a small granularity space,and the optimal solution with the largest comprehensive consistency is obtained by searching in this smaller granularity space.Finally,the feasibility and validity of the proposed method can be verified by an example,and the computational complexity can be reduced effectively.