The invention discloses a limiting damping mechanism for spray rod rotation used for a boom sprayer. The mechanism is installed between a static spray rod and a dynamic spray rod of the boom sprayer,wherein the dynamic spray rod is rotatably connected with the static spray rod; the mechanism comprises a limiting base fixedly connected with the static spray rod, a limiting rod is installed in thelimiting base in a sliding mode, the limiting rod in the limiting base is sleeved with a buffering spring, one end of the limiting rod extends out of the limiting base and is connected to an adjustment device for spring pre-pressing and deformation, a buffering limiting device connected with the limiting base in a sliding mode is installed on the limiting rod, the other end of the limiting rod extends toward the dynamic spray rod and is provided with a pressing leaning part, and a buffering leaning ear matched with the pressing leaning part is arranged on the dynamic spray rod. By means of thelimiting damping mechanism, not only can rotation when a stretching action of the dynamic spray rod ends be limited, but also impact and vibration caused by rotating inertia force generated when thestretching action of the dynamic spray rod ends can be reduced, so that balance and the safety of the sprayer are improved, and the service life of the sprayer is prolonged.