The spraying efficiency can be greatly improved by using pipeline spraying in larger orchard, meanwhile, labor strength could be reduced greatly and the pest control efficacy could be improved. Adopting constant pressure control devices can improve the stability of liquid pressure in pipeline, reduce the liquid pressure fluctuation which caused by the changing of spraying nozzles number. The spraying experimentations were carried in orchard by using constant pressure controller. Experimental result indicated that, using the constant pressure control device, the control error was 0.0167Mpa, the pressure control stability was 98.33%, the downtime to prevent pipeline bursting was 8.04s and the downtime after pipeline burst accidently was 8.88s. Using constant pressure controlling, stability of liquids pressure in the pipeline could be guarantee and pipeline bursting could be prevented at the same time.