The invention provides a method and a system which are used for arranging a tube in a body cavity quickly. The invention comprises the following steps: arrange a flexible cannula (140) at the probe tip (130) of a cutting device till the probe tip extendedly exceeds the cannula; cut the tissue covering the body cavity so as to form an opening in the body cavity; insert the probe tip of the cutting device till the cannula arranged the probe tip is input into the cut; remove the probe tip, and at the same time keep the cannula inserted in the cut; the far end or tip of the tube (145) is led into the preset distance in the cannula; remove the cannula on the tube, and simultaneously keep the tube at the position in the body cavity.