Arrow type back pressure valve is an important tool preventing of blowout. The design of the arrow type back pressure valve allows for an on-site determination of back pressure to be set at surface. The tool should be connected to needed drilling position in operation.Under normal drilling condition,drilling liquid pass through valve body and water channel to furnish downward.When happened well kick and blowout, underground pressure impel valve body to move upward 14degree pyramidal face of valve body is fitted tightly against gasket pyramidal face,they can prevent drilling liquid within the drilling from gushing and blowout upward.