Abstract: In this paper, a new method for inferring phylogenetic trees in cladistics is proposed. The design of the method is discussed and the procedure for practical algorithm is made clear. An example is given as an illustration for the method. Finally, some concepts of parsimonius coefficient, ideal solution, ideal method, optimal solution and optimal method are defined for comment on cladistic algorithm method. The evolutionary extremal aggregation method belongs to ideal method and then it is valuable for the quantitative cladistic analysis.