With the efforts of genome-sequencing technology, phylogenetic reconstruction based on molecular information requires massive computation. In this way, mathematical method, computer technology and other auxiliary means play key roles in enhancing the efficiency and accuracy of phylogenetic reconstruction. Maximum parsimony is a very important method for phylogenetic reconstruction, and it needs efforts of both biologists and computer scientists to enhance its computational efficiency. Herein, this article elaborated calculating flow of maximum parsimony in details and analyzed influences of parameter selection on computational efficiency, in order to help more computer researchers to present better, quicker and more precise solutions to phylogenetic reconstruction in practice. In the meantime, it tries to explain constructing thought and computational logic of maximum parsimony clearly for phylogenetic researchers, in order to push forward continuous improvement and optimization of using maximum parsimony in biology.