Abstract: In comparing with the method of multiple steps pumping flow, the method of one-step pumping flow for determining well loss constent and hydrogeological parameters given in this paper can at least reduce two times of changing flow abrutly in well flow test, so that the time of test can be shortened. Both linear regressive method and linear graphics method were introduced. A test on the practical example showed that the results abtained by two methods mentioned above are quite coincided with each other. But in the field test for determining well loss constant and hydrogeological parameters the method presented in this paper took only holf of the time in comparing with the method of multiple steps pumping flow.