This paper proposes the Hartmann ray tracing method to measure the gas -phase parameters of the gas-liquid two-phase flow,and conducts theoretical and experimental re search.First,the Hartmann template is used to obtain the array beam,and the propagation process of the light in the gas- liquid two-phase flow is simulated and traced to study the relationship between the emitted light and the bubble size and position in the two-phase flow.Second,the BP neural network model is est ablished to achieve accurate inversion of bubble parameters.The simulation results show that the relative error of bubble positioning is within 7%,and the relative error of bub ble size is within ±4%. On this basis,an experimental system is built to simulate the process of a sin gle gas phase passing through the pipeline with transparent particles of known size settling in a vert ical pipeline.Experimental research is carried out.The results show that the relative error of bubble s ize can be controlled within ±6%.