Abstract: As drilling across formation with fault or crust of different pressure system, it is easy to incur circulation loss and borehole collapse, and seriously it will cause well abandoned. TK4-3-1 handled for 112 days, used bridge paste, cement paste, composite bridge and cement, and mixture of water shutoff material and used regular and little volume of injection seal material but not success, finally used mixed water packing material with little volume injection and sealed circulation loss successfully, it is the only well handled successfully at the same condition of circulation loss, and it has accumulated experiment for handling complex circumstance of the same well.