A novel radio frequency identification（RFID） circular tag sensor was proposed for crack detection of aluminum structure in machine tools.Electromagnetic simulation software HFSS was used to simulate the crack length and position change of aluminum structure, and the S11 coefficient curve of the label sensor was obtained, the analysis showed that the resonant frequencies f01 and f10 decreased with the increased of crack length. The resonant frequencies f01 and f10 in the S11 coefficient curve were processed respectively, and the linear equations of the magnitude of resonant frequencies f01 and f10 and the crack length were obtained. By analyzing the absolute slope values of different linear equations, different crack locations correspond to different absolute slope values were obtained. The results show that the absolute slope values are the largest when it is at the center of the sensor, and the more the crack offset the center of the sensor, the smaller the absolute slope values are. The HFSS simulation results verify that by using the proposed novel 〖JP+1〗RFID circular tag sensor, the length and position change information of the aluminum structure crack of the machine tool can be detected.