To quantitatively detect the bubble size (cross-sectional diameters of bubbles), bubble frequency, and bubble rising velocity in gas-liquid two-phase flow, this study proposes a method for quantitative detection of the bubble characteristic parameters based on optical fiber spectroscopy. First, an optical system for the detection of bubble characteristic parameters is constructed with the near-infrared optical fiber spectrometer, plano-convex lens, multi-mode silica optical fiber, high-speed camera, gas-liquid two-phase flow pipeline, and syringe pump. Second, the theoretical models for quantitative detection of bubble size, frequency, and velocity in gas-liquid two-phase flow are built. Third, Zemax is used to simulate and analyze the optical transmission path in the optical measurement system. Finally, the performance of the optical measurement system in quantitative detection of bubble characteristic parameters is experimentally studied. The results indicate that the bubble size, frequency, and velocity in gas-liquid two-phase flow can be detected quantitatively by the proposed method, and the maximum relative detection errors of them are 9.8%, 8.1%, and 8.7%, respectively.