The sensitive galvanometer allows very little current to pass through，so in the process of experiment，the two-stage voltage division method is used to make the voltage at both ends of it very little．During the measurement，the variable deflection method is used，where we keep the total voltage U and the division voltage resistance Ｒ 2 unchanged，change the external circuit resistance Ｒ，and measure the corresponding deflection lattice number d．When processing the data，Origin software is used to fit the Ｒ～1/d curve，from which the slope and intercept of the straight line can be obtained，thus the current constant k and the internal resistance Ｒ g of the sensitive galvanometer can be obtained．Compared with manual drawing，the Origin mapping method is much faster to fit data，and it is worth to be extended to other experiments in the college physics experiment course．