The invention discloses a solid dissolving and injecting system with the circular flushing and accurate dissolution control functions. The solid dissolving and injecting system comprises a spray flushing and dissolving pond with the upper portion opened, a spray head is correspondingly arranged above an opening of the spray flushing and dissolving pond and is connected with a spray water supply pipeline, and a spray tank filtering net is laid in the spray flushing and dissolving pond and divides the spray flushing and dissolving pond into an upper spray flushing and dissolving pond body and a lower spray flushing and dissolving pond body; a dissolving solution collecting pond is arranged below the spray flushing and dissolving pond and is connected with a dissolving solution injecting pipeline, a spray flushing and dissolving pond outlet is formed in the bottom of the lower spray flushing and dissolving pond body, and the dissolving solution collecting pond is connected with the spray flushing and dissolving pond outlet. By means of the own hydrodynamic force of the head of an irrigation system, solid fertilizer (pesticide) is dissolved and injected, circular flushing and accurate control are achieved, and it is ensured that being dissolved thoroughly, the solid fertilizer or pesticide does not block a drip irrigation pipe.