A facile preparation of a mesoporous Cr-MOF, PCN-333(Cr) with functional group, has been demonstrated through a dual exchange strategy, involving a sequential ligand exchange and metal metathesis process. After optimization of the exchange system, the functionalized PCN-333(Cr), N-3-PCN-333(Cr) shows well maintained crystallinity, porosity, as well as much improved chemical stability. Because of the exceptionally large pores (similar to 5.5 nm) in PCN-333(Cr), a secondary functional moiety, Zn-TEPP with a size of 18 angstrom X 18 angstrom, has been successfully clicked into the framework. In this article, we have also analyzed kinetics and thermodynamics during dual exchange process, showing our attempts to interpret the exchange event in the PCN-333. Our findings not only provide a highly stable mesoporous Cr-MOF platform for expanding MOP-based applications, but also suggest a route to functionalized Cr-MOF which may have not been achievable through conventional approaches.