Through a less-investigated in-situ hot-pressing synthesis method, the phosphotungstic acid H3PW12O40 (denoted as PW12) was rapidly incorporated into a metal-organic framework MFM-300(In) in a short time, affording novel PW12@MFM-300(In) composites. This solvent-free preparation process is not only environment-friendly but also energy/time-saving. The inclusion of PW12 in MFM-300(In) was demonstrated by different physical and chemical characterizations. It was interesting to fmd that PW12@MFM-300(In) as new heterocatalysts display synergistic activity for the visible-light-driven catalytic degradation of pharmaceutically active compound sulfamethazine (SMT). 4-PW12@MFM-300(Ln) with excellent robustness possesses the high removal efficiency of about 98% toward SMT within 2 h at room temperature, and can also be recycled multiple times for this catalytic process.