For high power laser of low cavity pressure, a new type of aerodynamic window using jet injection is researched and produced. Experimental study shows that for a φ6.5 mm free aperture, by only using jet injection the sealing pressure can achieve about 0.1 atmophere and the flow of jet injection has no considerable influence on the intensity distribution of the laser beam. As both jet injection and suction are used the sealing pressure can drop down till 66. 5 Pa. The experiment also shows that the sealing pressure can be easily adjusted and stabilized.