Obiective　To evaluate the accuracy of the measurement of diameters about percutaneous radiofrequency thermocoagulation of the trigeminal ganglion under neuronavigation system.　Methods　The diameter of foramen ovale and the depth of needle in trigeminal ganglion blocking was measured with different surgery methods through neuronavigation system, CT images and standard scientific calipers, respectively. The equivalence and stability of the three measurement methods were evaluated.　Results　The average length of foramen ovale on basalis samples, CT images and neuronavigation system was （8.42±1.38）mm, （8.46±1.34）mm, （8.50±1.42）mm, and the average breadth was （4.57±0.88）mm, （4.62±0.88）mm, （4.63±0.95）mm accordingly. Compared with values on the cadavers, the values of other two measurement showed no statistic difference (P>0.2). The results of the coefficience of variation(CV) of the three groups showed that the values obtained through the CT image group was the smallest, next to which is the values obtained in cadavers. The distance from the anterolateral border of foramen ovale to the anterior puncturing point was （64.26±8.09）mm, （64.72±8.29）mm in cadavers and neuronavigation system, respectively; the distance from lateral border of foramen ovale to the lateral puncturing point was（42.03±4.17）mm, （42.31±4.36）mm respectively. The values of two groups showed no significant difference (P>0.2). The CV on the group of cadaver was slightly smaller than that of the group of neuronavigation.　Conclusion　The diameters of foramen ovale and the depth of needle in trigeminal ganglion blocking can be measured on neuronavigation system accurately.