Expert’s opinion consensus is one of key problems in the War Design Engineering. Firstly, the characteristics of experts thought, such as adaptive, cluster and non-linear, are analyzed from the view of complex theory. According to their interactive relationship, experts are divided in to two categories, and the convergence process is modeled by Markov transmission matrix. Then, the necessary and sufficient conditions of reaching consensus for each category experts are presented and proved. It ends with the conclusion that the condition of experts thought convergence is not only relative to interactive relationship matrix, but also the primal opinion of expert. Finally, some propositions are verified by computer simulation.