The invention discloses a construction method of a sponge road and a device thereof. The device comprises a longitudinal-side transverse groove cement foundation, an inverted-V-shaped bridge hole elliptical frame electromagnet concave-convex modular monomer, a module combination, a pressure-bearing and blocking framework, a panel, a right-angle triangular frame, asphalt, cement concrete, a suction pressing iron plate group, an alternating magnetic field and a dragging framework. A front convex electromagnet and a back concave electromagnet are matched with each other in a concave-convex way, connected in series into a strip, and placed into a same-length wider cement foundation transverse groove to be fixed. The pressure-bearing and blocking framework is longitudinally placed on an outermost side of an electromagnetic line module combination to play a role in bearing pressure and blocking. The asphalt is placed on an electromagnetic module, an iron plate is placed on the asphalt, a medium and low-frequency alternating magnetic field is set, a strong magnetic field is obtained by low conducting current, and the iron plate is pressed down after the action of strong suction force generated after the electromagnet is powered on. The asphalt is pressed and molded, and a formed arch-shaped space is an underground drainage ditch. Very strong diversion and drainage effects are achieved, and water accumulation is prevented. The underground drainage ditch supports a road surface to prevent the road surface from being damaged in a collapse way. The normal period of the road is long, and the cost performance is high. The sponge road has a wide application range, and has great environmental protection and economical significance.