The painting of large construction and engineering machinery needs to consider aesthetics and equipment protection. Manual spraying is flexible and suitable for complex shapes; Air spraying is suitable for large-area flat surfaces; High pressure airless spraying is suitable for thick coating requirements; Electrostatic spraying is suitable for high-quality coatings; Automated spraying is efficient and stable. The selection of spraying method requires comprehensive consideration of coating requirements, workpiece shape, and coating efficiency.