Threedimensional physical models of oilair lubricated ECT sensors of UMIST type (with axially grounded shield electrode) and METC type (with axially driven shield electrode) were established.Based on the threedimensional physical models,the mathematical expressions of capacitance value and sensitivity were derived,and the influence of the axial shield electrode on the sensor sensitivity and the uniformity of sensor sensitivity was analyzed.Linear back projection (LBP) algorithm was used to reconstruct the image,and the relative error and correlation coefficient between the reconstructed image and the real image were compared.The results show that both axial shield electrodes can eliminate fringing capacitance and improve the sensitivity of the sensor.Sensitivity influence coefficient characterizes the uniformity of sensor sensitivity.The axially grounded shield electrode makes the sensitivity of the sensor more uniform,while the axial driving shielding electrode has the opposite effect.METC type ECT sensor is more suitable for the recognition of annular flow in oilair lubrication,the relative error between the reconstructed image and the real image is reduced by 28.79%,and the correlation coefficient is increased by 14.05%.