A stable hierarchical porous metal–organic framework PCN-56 with abundant Lewis acid sites (denoted as Defective-PCN-56) was synthesized by the low-temperature synthesis-induced defect formation method. The existence of mesopore in structure was confirmed by N2 sorption isotherm and the successful encapsulation of large dye molecules. The Defective-PCN-56 has higher loading capacity toward anti-cancer drug Doxo compared with that ofnearly ideal-crystal(denoted as Ideal-PCN-56) synthesized at high temperature, showing potential application as drug carrier. The low-temperature synthesis-induced defect formation strategy presented here provides a new and facile way to synthesize stable MOFs with the combination of intrinsic micropore and additional mesopore as well as abundant Lewis acid sites.