Abstract: Aiming at the deficiency of the existing single-wavelength method in measuring the phase distribution parameters of the vertically rising gas-liquid two-phase bubble flow in a small channel, a dual-wavelength method is proposed. Based on the principle of geometric optics, the light intensity distribution of dual-wavelength laser passing through gas-liquid-two-phase-flow is calculated, and the characteristics of light intensity distribution of dual-wavelength laser are extracted. An identification model of bubble flow phase distribution parameters based on the dual-wavelength measurement theory is established. Trace Pro is used to simulate 445 nm and 635 nm laser passing through bubbles with different phase distribution parameters, and then the features of the dual-wavelength light intensity distribution curves can be extracted. The characteristic quantity data set of simulation is used to train the neural network. The trained neural network is used to predict the phase distribution parameters of bubble flow in the experiment. The simulation results show that the average absolute errors of the model for predicting the bubble center position and radius are 0.018 mm and 0.007 mm respectively, which are better than the single-wavelength method, which proves the effectiveness and accuracy of the model. The bubble flow was measured on the experimental platform, and the three-dimensional diagram of bubble flow was reconstructed.