In order to deepen the peaceful development of cross-strait relations,both the Mainland and Taiwan should form an agreement of two side,one China.Now Taiwan usually looks for the agreement of based on respective governance of cross-strait.Both one-China roofand one China,three constitutions are all so.The main problem of this idea is that it will weaken framework in the actual operation.To overcome this drawback and strengthen two side,one China,the Mainland and Taiwan may form the tacit agreement of inter subjectivityand inter special area.