Abstract: Drill cuttings gas desorption index K₁ value is an important indicator of outburst prediction and effect testing.Accuracy of test results directly affect whether there is a outburst risk in coal seam.Laboratory and field studies found that the mixed sample was an important factor in affecting the accuracy of outburst forecast.Through field test,using positional sampler can solve the problem of mixed sample and improve the forecasting accuracy,which ultimately can effectively prevent the occurrence of the so-called "low-index outburst ".