The invention provides a construction method for pouring tunnel second lining self-compacting concrete. Firstly, pouring is conducted from a waist window on the single side for storage, and then a top pouring mode is switched. The construction method comprises the steps that a ground pump pipe is arranged for storage, specifically, after formwork erection of a trolley is finished, the pump pipe is connected into the trolley, and the pump pipe is guided to an observation window on one side through a hose for storage; concrete at the bottom of formworks is poured, specifically, the concrete poured from the single side for storage flows from one side to the other side till the lower observation window is closed; and pipe switching is conducted, specifically, the hose is moved out from the side pouring window and connected with a corresponding top pouring hole till pouring is finished. By the adoption of the construction method, on one hand, applicability selection of the ground pump power in the pouring process of an all-round-formwork trolley of the self-compacting concrete is achieved; and on the other hand, reinforcing bar reveal and retention of the bottom concrete are effectively avoided, finally the construction quality of concrete structure formation is improved, and the construction efficiency is improved.