In order to improve the mechanized spraying effect of stunted and close planting cotton, an air-assisted cotton boom sprayer with separating row and spraying in inside and upper canopy by combining separating row and spraying inside canopy technology with air-assisted spraying technology was designed. This sprayer braced the droplet diffusion space of inside cotton canopy by row separator and improved droplet diffusion range and distribution uniformity by airflow disturbance and transport of inside and upper cotton canopy.