The utility model discloses a flushing type sand cylinder support structure comprising a sand cylinder, fine sands and a concrete body, the fine sands and the concrete body are arranged in the sand cylinder, the concrete body is arranged on the fine sands, and a sand outlet hole is formed in the bottom of the sand cylinder, so that water flushes fine sands at the bottom out of the sand outlet hole in the dismounting process, the concrete body sinks, and then the support can be dismounted. The problems that when an extremely-low headroom track beam support of an urban elevated station is dismounted, the construction period is long, the cost is high, and investment is high are well solved. The flushing type sand cylinder support structure is applicable to the field of buildings.