The laser output power of the dimer of O2 (1Δg) was estimated theoretically. By means of microwave (2.450GHz) exciting high pure oxygen to generate the dimer of O2(1Δg) in experiments, the laser oscillation of the dimer of O2(1Δg) was realized at 656 nm for the first time with stable flat-concave resonator. When the pressure of oxygen was 133.3Pa, the power of microwave was 600W, the laser power was as high as 100 μW, this corresponded to theorectical estimation in order of magnitude. In addition, the diverge angle measured was about 37.3 mrad.