The invention relates to the technical field of deep foundation pit construction, in particular to a construction method for carrying out pressure reduction water control treatment when confined groundwater bursting happens to a deep foundation pit. The method comprises the following steps that S1, well hole drilling is carried out and well drilling is carried out at the bursting position of the deep foundation pit; S2, a filter material bag is put in a hole, and the filter material bag is put into the well hole for bottom pressing; S3, a well tube is manufactured and hoisted, and the well tube is overall hoisted into the well hole; S4, the space between the hole well and the well wall is filled with materials; S5, a filter material bag is put into the well tube, water is drawn, the filtermaterial bag is put into the bottom of the well tube, then an immersible pump is lowered, and confined underground water in the well tube is drawn out; and S6, well sealing is carried out, the well hole is sealed, and foundation soil is subjected to grouting filling reinforcement treatment. The method has the following effects that the confined groundwater is temporarily stored in the well hole,the confined groundwater at the bursting point is controlled, after the confined groundwater is constantly drawn out, the well hole is closed, and therefore the confined groundwater bursting quantityunder the conditions of the high pressure and the large water quantity is reduced, and the water control effect is improved.