Software architecture design is one decision-making process for a series of major issues from software development and the best practices had been summed up. Nevertheless, the strict observance of the best practices still cannot raise the design line from the class development to framework development. The reason was that most imitators are unable to understand accurately the essence of two key words of "iteration" and "divide and rule". Therefore, this paper made further study of the "iteration" and "divide and rule". First, the meaning of "iteration" would be redefined. It is that each cycle should have a respective emphasis and end with the time deadline so as to make a clear distinction among them and improve iterative efficiency. Second, the meaning of "divide and rule" would also be redefined. It is that the passive decomposition based on Test First is better than active decomposition. Because it is the most suitable to have no alternative but to decompose according to current concrete conditions. By this way, best practices of architectural design can be implemented in real project, so as to improve the level of architecture design in essence.