The invention discloses a dewatering construction method for a deep foundation pit combination well of a pressure-bearing phreatic water aquifer. Compared with a construction way which needs to simultaneously arrange a dewatering well and a water-lowering well in the prior art, the dewatering construction method has the advantages that a single well can be used to complete the technical effects which only can be reached by two wells in the conventional technology, the single well is used to complete synchronous dewatering for phreatic water aquifer and a ground layer of a pressure-bearing phreatic layer, and the purposes of reducing engineering cost and improving environment friendliness of underground water are achieved.