Composite plugging agent (plugging while drilling) is madefrom nature polymer based composite, it can be used well in drilling. Because it swells when meets with water, so it has the capacity of plugging, it also has strong adhesive ability, compared with traditional plugging agent, it can be used more expediently, it can combined with all mud system to plug the thief zone and protect low-pressure production zone (oil, nature gas, water, etc.).