The crisis of legitimacy is spurring reform of international investment arbitration. The reform direction of international investment arbitration is in a state of different opinions, opposite opinions and unknown direction. Its core lies in the dispute between "commercialization" and "de-commercialization" of investment arbitration. From the perspective of inevitability, the "commercialization" of international investment arbitration is controversial. The theory of commercial arbitration may have legitimacy and legality problems when solving the investment disputes concerning a sovereign state. From the perspective of reality, the ICSID investment arbitration mechanism which is borrowed and used to commercial arbitration runs well in general, and it has become a trend that more and more commercial arbitration mechanisms adopt commercial arbitration rules to govern investment disputes. Both theoretically and practically, the "commercialization" of investment arbitration is desirable, and the commercial arbitration mechanism should be allowed and encouraged to govern investment disputes. Under the trend of "One Belt and One Road", China should establish an influential and internationally competitive Chinese investment arbitration mechanism based on the commercial arbitration institutions that have issued the investor-host country arbitration rules.