Abstract: It is crucial to understand the internal mixing behavior accurately of the fuel assemblies in the nuclear reactor which could optimize design and safety analysis. The wire-mesh sensor can measure the flow channel cross-section with high spatial and temporal resolutions. At present, the fine measurement of single-phase mixing based on the wire-mesh sensor combined with the mass balance method has been relatively mature, but it lacks the method of measuring concentration field in the two-phase intersection mixing. Therefore, a two-phase concentration inversion algorithm was proposed in this paper, which could realize the synchronous measurement of the void fraction field and the liquid phase concentration field in the complex flow field. In order to verify the feasibility and accuracy of this algorithm, numerical simulation and experiments were carried out. In calculating the porosity, Maxwell equation was used. COMSOL multiphysics was applied to simulate the gas-liquid two-phase flow field, including simulating the flow field with different concentrations of single bubble and multi-bubble, and adjusting the concentration distribution by changing the conductivity parameters. The simulation method of the wire-mesh sensor was to set two layers of wires as the receiving and emitter of the sensor. The potential of the excited transmitting line was set to 1 V in turn, and the potential of the unexcited transmitting line and the receiving electrode line was set to 0 V respectively. By simulating the single bubble fluid domain, the two-phase concentration inversion algorithm was finally obtained by comparing the candidate algorithms, and the variable concentration field was established in the multi-bubble simulation domain. The simulation results show that the algorithm is suitable for the two-phase mixing precision measurement and has high accuracy. In this paper, the method was verified by the experiment of square tube channel synchronous measurement at normal temperature and pressure. Based on 8×8 wire-mesh sensors, void fraction and concentration distributions could be measured and calculated. The experimental measurement position was located at 0.8 m of the square tube channel, the sampling frequency was 5 000 Hz, and the single sampling time was 20 s. The bubble generator was installed at the bottom of the experimental device to achieve gas-liquid mixing during the experiment. The bubble generator was designed with 12 holes with 1 mm diameter. The gas phase flow range was set to 0.12-0.3 m³/h, and the flow rate was adjusted through the rotary flowmeter. There were four different concentrations of potassium chloride solution. The experimental results show that the peak value of the void fraction is distributed in the center of the square channel and decreases gradually with the approach of the void fraction. It is found that the concentration distribution is relatively uniform and can be accurately measured, which proves the applicability of the synchronous measurement method.