The measurement of inner diameter is a traditional and important measurement task in machining. Methods to measure the inner diameter are divided into contact and non-contact measurement. A contact measurement method with multiple inductive transducers is presented in this paper. In this paper, the constitution and structure of the system are described in order to establish the mathematical measurement model and analyze the measurement error emerged by inaccurate parameters. Moreover, the outputs measured by sensors are transformed into corresponding coordinates, and then the least square method is adopted to fit the coordinates to calculate the diameter, details will be presented in the paper. The measuring accuracy of the system is verified by experiment. The results indicate that this method could reduce the error caused by sensors deviated from the center of measuring circle and improve the measurement accuracy.