During data collection

the experimental data such as curve of force versus displacement are usually disturbed by the environmental uncertain signals

which cause the data to drift greatly.Since the drift is stochastic

uncertain

and has distorted the real experimental curve severely

it brings lots of difficulties in analyzing the experiment results.In this paper

based on the characteristic of the stochastic disturbance signals

a three-phase digital filter arithmetic is given

in which the disturbance signals are filtered in each phase gradually

according to the different filter methods

and then the real curve is reappeared again.Two idiographic and different instances are adopted to prove the validity of the arithmetic at the end.