A new type of molecularly imprinted polymer (MIP)-based room-temperature phosphorescence (RTP) optosensor was developed by anchoring the MIP layer on the surface of Mn-doped ZnS quantum dots (QDs) via a surface molecular imprinting process. The synergetic combination of the RTP property of the Mn-doped ZnS QDs and the merits of the surface imprinting polymers not only improves the RTP selectivity of the Mn-doped ZnS QDs but also makes the MIP-based RTP optosensor also applicable to selective detecting of those nonphosphorescent analytes without the need for any inducers and derivatization. The new MIP-based RTP sensing protocol was applied to detect trace pentachlorophenol (PCP) in water samples without the interference of autofluorescence and scattering light of matrixes. The detection limit for PCP was 86 nM, and the precision for five replicate detections of 0.4 microM PCP was 2.8% (relative standard deviation). The recovery of spiked PCP in river water samples ranged from 93% to 106%.