The invention discloses a process method for preparing active calcium oxide by oxygen-enriched calcination. The process method the following steps of firstly crushing and sieving raw limestone to enable the particle size of the raw limestone to be 10-55 mm, conveying the raw limestone into a stock bin with a circular cross section, wherein the stock bin is arranged at an upper part of a vertical preheater; then, uniformly conveying the raw materials in the stock bin into the vertical preheater through a blanking pipe, and preheating the raw materials by using high-temperature kiln gas and cooling gas of a vertical cooler; then, feeding the materials into a rotary kiln, and importing oxygen-enriched air from a kiln head to perform oxygen-enriched calcination; and then, feeding the calcium oxide obtained after calcination and decomposition into the vertical cooler to be cooled by air, namely, obtaining the active calcium oxide. According to the process method disclosed by the invention,through the integration of the processes of graded preheating, oxygen-enriched calcination, graded cooling, dynamic temperature monitoring and the like, and the raw materials are preheated by combining the high-temperature kiln gas and the high-temperature gas discharged from the cooler, the heat transfer efficiency of the system is greatly improved, the activity of calcium oxide is obviously improved, the energy consumption is reduced, and the energy conservation and emission reduction are realized.