Abstract: Uncontrollable blowout is a great drilling accident. For gas kick during drilling, in order to prevent uncontrollble blow-out, the gas-liquild two-phase flow model is established, considering the kick characteristics in well kick and well killing process, and it is solved with finite difference method, given initial values in different periods. The results indicated that a one-to-one correspondence was established between standpipe pressure and kick rate and height while drilling, and another one-to-one correspondence was also established between casing pressure and kick rate and height while well killing. Based on the findings above, the standpipe pressure method and casing pressure method were proposed to detect kick, and the related coefficient method was used to judge the kick rate and height during drilling and killing. Meanwhile, a computer system was developed to judge kick velocity and height automatically, which provided a theoretical basis for kick parameter judgement.