The invention relates to the technical field of automobiles, in particular to a four-valve variable valve lift mechanism and a control method thereof. When an engine needs to output large power, a fourth electromagnetic valve and a second electromagnetic valve act on a first sliding sleeve on a first motion unit and a second sliding sleeve on a second motion unit successively so that large-lift cams on the first motion unit and the second motion unit are matched with a valve, so that the valve is in the large-lift state; when the engine needs to output small power, the first electromagnetic valve and the third electromagnetic valve are matched with small-lift cams of the first sliding sleeve on the first motion unit and the second sliding sleeve on the second motion unit and the valves successively, and the valves are in the small-lift state; the output power of the engine is adjusted. The technical problems that in the prior art, a switching mechanism normally adopts a hydraulic control mode, the hydraulic control temperature influence is large, the manufacturing cost is high and the mechanism is complex due to combined-fit design of a cam shaft and a roller rocker arm are solved.