Abstract: In order to describe the uncertainty of the location of typhoon vortex center more reasonably in ensemble forecast, the uncertainty characteristics of the location of typhoon vortex center in the best track of typhoon were analyzed by using the data of the China Meteorological Administration and Japan Meteorological Agency from 2009 to 2018. On this basis, the method of Conditional Typhoon Vortex Relocation (CTVR) is designed, and the threshold conditions of Typhoon Vortex Center Relocation, the mathematical processing of typhoon vortex separation and the mathematical processing of typhoon vortex relocation are constructed. Based on the Global/Regional Assimilation and Prediction System-Regional Ensemble System (GRAPES-REPS) of Numerical Weather Prediction Center of China Meteorological Administration , the ensemble forecast experiments and test of two schemes of axisymmetric structure and axisymmetric plus asymmetric structure Conditional Typhoon Vortex Relocation for three typhoons (Maria (1808), Tarmi (1824) and Kong (1825)) over the Northwest Pacific Ocean in 2018 were carried out. The results show that: (1) The mean error of the observational track of typhoon between China Meteorological Administration and Japan Meteorological Agency is 13.72 km, which can be regarded as a reasonable estimate of the uncertainty of typhoon vortex center location. (2) Statistical test results and typical case analysis show that typhoon ensemble forecast track error and ensemble forecast consistency using axisymmetric structure and axisymmetric plus asymmetric structure CTVR are comparatively close. (3) The method of CTVR can effectively improve the probabilistic prediction effect of typhoon track in GRAPES-REPS. For example, the mean error of ensemble forecast of typhoon track is reduced, and the consistency of ensemble forecast (the ratio of track spread to Root Mean Square Error of track) is increased, especially in the initial stage, the improvement of probabilistic prediction effect is more remarkable, while the improvement in the middle and later stage is limited. (4) Through the diagnosis and analysis of Maria typhoon ensemble forecast, it is found that after the CTVR, the typhoon track error of each member obviously decreases and the track converges in the early stage of forecast, but with the increase of forecast time, the typhoon track gradually diverges. After using the method of CTVR, the typhoon vortex circulation and the large-scale environmental field are still in continuous coordination, and the large-scale environmental field outside the typhoon vortex circulation has the characteristics of consistency. In addition, the error of minimum atmospheric pressure, the error of maximum wind speed and the skill of precipitation forecast are basically unchanged. It can be seen that the application of CTVR method can provide more accurate information of the uncertainty of typhoon track prediction and help forecasters to make more accurate prediction decisions.