Abstract: The traditional method of K1 determination which uses twist drill pipe mechanical sampling is greatly influenced by the residual powder of the hole wall and unable to accurately define the coal samples exposure time. This will lead to the problem that effectively prediction depth of outburst danger of mining face is shallow and reliability of deep hole prediction is low. To solve the above problem, reverse circulation sampling technique based on double-wall drill pipe is put forward for the determination of K1 value. This technique can make the hole drilling cuttings at the bottom be transported to the drilling external to achieve rapid, fixed-point sampling, so that it will avoid the problems existing in the traditional sampling method. K1 value determination test that uses reverse circulation sampling technique in Wu lan coal mine show that K1 values predicted depth can be up to 30 m, and is not affected by borehole inclination.