The downhole annular flow electromagnetic measurement system can obtain real-time downhole annular flow information. However, the gas invaded by the annular flow channel affects its measurement results. The measurement system cannot accurately warn the overflow and blowout problems during the drilling process. To address the problem that the annular flow electromagnetic measurement system is affected by gas intrusion, the research firstly obtains the virtual current density function of the annular flow electromagnetic measurement system by formulating the theoretical model of the influence of gas intrusion on the annular flow electromagnetic measurement system. Secondly, the finite element simulation is used. The software dynamically simulates the different existing states of the invading gas, and analyzes the virtual current distribution law of the annular flow electromagnetic measurement system. Experimental results show that as the gas content of the two-phase mixed fluid in the annular flow channel increases in the range of 0% ~ 5% , the output voltage of the annular flow electromagnetic measurement system under different two-phase mixed flow rates shows a downward trend. The relationship between the output voltage and gas content of the annular flow electromagnetic measurement system under different two-phase mixed flow rates is fitted by the quadratic function. The coefficient of determination R 2 is above 0. 98, and the fitting residual e is less than 0. 011. The relational corrected annulus measures the flow. The research results can be used to reduce the influence of gas intrusion on the measurement results and improve the measurement accuracy of the downhole annular flow electromagnetic measurement system.