The invention relates to a detachable type impeller seal head structure for an excavating pump, and belongs to the fields of fluid machinery and fluid power engineering. The impeller seal head structure comprises a seal head body, a seal ring and a check ring; a step-shaped cylindrical seal head mounting hole is formed in the front end of an impeller shaft hole by processing; the outline of the side wall of the seal head body is matched with inner shape of the seal head mounting hole in the front end of the impeller shaft hole, a check ring clamp groove is formed in the rear end of the side wall of the seal head body, and a thread blind hole for detaching is axially formed in the front end surface of the seal head body; the seal head body is mounted in the seal head mounting hole formed inthe front end of the impeller shaft hole and is downwards axially limited relative to an impeller through the step-shaped cylindrical structure; the check ring is clamped in the check ring clamp groove formed in the rear end of the side wall of the seal head body, and the seal head body is forwards axially limited relative to the impeller through the check ring; the seal ring is mounted in a sealring clamp groove in the side wall of the seal head body.