This work describes a convenient method to generate a poly(dimethylsiloxane) (PDMS) composite containing Zno quantum dots (QDs) for whole-chip temperature measurements. This composite is highly fluorescent and very sensitive to temperature changes (0.4nm degrees C-1, compared to 0.1 nm degrees C-1 in commonly used CdSe QDs). It also shows extremely high fluorescent stability under various conditions over long time without phase separation or fluorescent changes. Both merits make this composite an ideal material for sensing temperature changes on microfluidic chips. The bonding between the QDs and PDMS is studied by comparing PDMS composites with ZnO QDs of different sizes, and a model is given to elucidate the high stability of this composite.