We propose a new pH sensing technology using fluorescence sensing based on quantum dots combined with optical fiber sensing based on evanescent wave, which owns the advantages of high sensitivity, fast testing, suitability for micro-environment measurement, remote detection, real-time monitoring, in situ analysis and so on. In this paper, we detail the preparation method of the combined taper-and-cylinder optical fiber probe for evanescent wave sensing, the modification process of quantum dots onto the surface of the optical fiber probe, the construction of two fiber pH sensing platforms based on spectrum and intensity, and the evaluation of the performance of CdSe/ZnS quantum dots applied for optical fiber pH sensing from the aspects of response range, linearity, repeatability and stability, respectively. The results show that in the pH range of 2 to 12, the fluorescence spectrum peak position of CdSe/ZnS quantum dots will produce a red shift in strong acid and alkaline, and the amount of the red shift has a linear relationship with the pH value. The fluorescence intensity of the CdSe/ZnS quantum dots also reduces linearly with the decreasing of pH value. Moreover, the alternating tests under the strong acid and strong alkali indicate that it is of good repeatability. The real-time monitoring experiment through the intensity sensing platform indicates that it has good stability. Therefore, it is feasible to combine CdSe/ZnS quantum dots and evanescent wave for fiber pH sensing, and this kind of fiber pH sensor would have a promising future for pH detection in the field of biochemistry, environmental monitoring, clinical medicine and food safety.