Water-to-air imaging is affected by waves when light penetrates the sea-air interface，which will bring unfavorable factors such as defocus，blur，and distortion to the image. When the wave has a positive slope，the vertical resolution of water-to-air imaging will be increased to a certain extent，which can improve the detection probability of the target. Theoretical analysis and simulation methods to quantify the change in the incident angle of the target in the air caused by the forward slope wave are used. The resulting vertical resolution stretch of the target is analyzed. The reliability of the theory is verified through experiments，which provides a basis for the design of the optical system and the evaluation of image quality.