The invention discloses an integrated device for measuring surface runoff flow and collecting runoff liquid step by step. The device comprises an integrated box, an integrated box body, the integratedbox body is internally provided with a deceleration regulator, a current divider box and a runoff collection box, and each collection box corresponds to a current divider box, each current divider box comprises at least two outlets, part of the outlet at the lower side of the current divider box is connected with the inlet of the corresponding runoff collection box, part of the outlet at the lower side of the current divider box is connected with the drain pipe, and the remaining part of outlet of the current divider box is connected with the inlet of the corresponding runoff collection box.the remaining part of outlet of the current divider box is connected with the inlet of the sub-level of the current divider box, the inlet of the deceleration regulator is connected with the inlet ofthe flow diversion pipe, the outlet of the deceleration regulator is connected with the inlet of the current divider box on the uppermost side, and the outlet of the runoff collection box is connectedwith a drain pipe through a drain valve. The integrated device for measuring surface runoff flow and collecting runoff liquid step by step has the advantages of small occupation area low constructionand small engineering; easy collection and cleaning of runoff water, no leakage, easy maintenance and low maintenance cost, and long service life.