The invention discloses a laser metal direct forming method of liquid argon jet cooling directional solidification. The method is characterized in that: positive temperature gradient is kept all the time along the Z-axis direction in a molten pool in the subsequent forming process by adopting a method of liquid argon jet and quick cooling performed below the formed layer once a certain layer number is stacked. Meanwhile, the liquid argon for cooling is converted into argon gas and can also be used for reducing oxygen content in an argon protection box. Therefore, the columnar crystal tissue in a formed piece is continuously grown from a substrate along the Z-axis forming direction, and the formed piece obtains complete directional solidification columnar crystal tissue.