The invention relates to an inner double circulation runner type stretchable pitch sprinkling device which mainly comprises a support frame, a fixed sprinkling rod component, a left stretching sprinkling rod component and a right stretching sprinkling rod component which are the same in structure, and a pitch sprinkling valve, wherein the fixed sprinkling rod component is mounted on the support frame; each of the left stretching sprinkling rod component and the right stretching sprinkling rod component comprises a primary pitch pipeline, a secondary pitch pipeline, a rotating joint, a side sprinkling pipe and a pitch sprinkling valve; each primary pitch pipeline, each secondary pitch pipeline and each side sprinkling pipe are all divided into an oil inlet channel and an oil return channel by separating plates; an inner flowing pipe with smaller diameter is arranged in each rotating joint; and a transmission gear is driven by a hydraulic motor which is mounted on the support frame and a transmission rack fixedly arranged on the left stretching sprinkling rod component and the right stretching sprinkling rod component is driven to do linear motion, so that expansion and retraction of the left stretching sprinkling rod component and the right stretching sprinkling rod component are realized. Without using an externally connected pipeline, the inner double circulation runner type stretchable pitch sprinkling device can realize pitch circulation; the sprinkling distributing width is wide; and the structure is simple.