The invention discloses an extra-deep downward concrete pumping system which is used for pumping concrete from a high terrace to a lower terrace. The extra-deep downward concrete pumping system comprises a conveying pump, a pylon and a pump pipe, wherein the conveying pump is fixedly arranged on the high terrace; the bottom of the pylon is fixedly supported on a bearing platform positioned at the lower terrace; the top of the pylon is respectively fastened on a pair of concrete piers positioned at the high terrace through a pair of tower crane attached legs; the pump pipe is erected on the pylon; and the input end of the pump pipe is connected with a pump mouth of the conveying pump. Due to the adoption of the extra-deep downward concrete pumping system disclosed by the invention, the system for conveying the concrete downward to an extra-deep area is realized; and the extra-deep downward concrete pumping system has the advantages of high conveying efficiency, stability and safety for conveying, low possibility of blocking the pipe and easy overhaul.