The paper introduces a tritium measuring instrument

in which technologies such as nuclear radiation detection

electronics

information processing

etc. have been incorporated. By using the gas-flow proportional counter

advanced microprocessor

as well as data and information processing technique

the instrument has a low power consumption and high detect efficiency. The experimental results show that the plateau length is 300 V;the plateau slope 0.608%/100V

the lower detection limit 0.221 Bq·cm-2(for 600 s)

the stability of the instrument 0.56%/h

the variance coefficient 2.88%

and the detection efficiency 84%(for the 2π surface emissivity of 3H source 1307/min-1).