The scanning probe is the core part of the high precision 3D thread synthetical measuring machine, its dynamic characteristics seriously affect the precision of the machine. In order to improve the precision of the measuring machine, the dynamic characteristics of the linear scanning probe for 3D size measurement of high precision thread are studied. Firstly, the measuring principle of the scanning probe used in the 3D thread synthetical measuring machine is analyzed, then the dynamic characteristic model is established and the factors affecting the dynamic measurement result are put forward. Finally, the dynamic characteristic of the probe structure and the effectiveness of the measuring processing method are verified through experiments. The experiment results verify the correctness of the influencing factors. Through optimizing the sampling spacing factor that has the greatest influence, 80% of invalid data points can be filtered, so that the mean residual sum of squares error of the fitting in this section is reduced by 91. 0% and the linear error is reduced by 67. 4% . The measurement accuracy of 3D thread measuring machine is improved.