Abstract: The amount of tritium retained in vanadium bed was measured by methods of direct measurement, isotope-exchange and dissolution. The standard deviations of three methods were separately analysed for the present experimental conditions. The results show that the percentage of tritium residual in the vanadium bed is 4.40%, and the standard deviation of PVT measurement method is less than 0.95%, when the pressure is between 1 500 Pa and 133 332 Pa. The average efficiency of isotope-exchange is 37.18% after isotope are exchanged time after time. Its standard deviation is 7.35%. Dissolution method can measure tritium in the V-bed completely, and its standard deviation is 6.49%.