Employing the intracavity absorption technique,Lamb dip of the spectrum was obtained and the resolution and sensitivity of CO Laser magnetic resonance(LMR) spectrometer was greatly improved. By this technique, the X2Π3/2(υ=1←0) Zeeman transitions of 15N16O were observed with the Λ-doubling and hyperfine structures resolved. A correlative analysis of the LMR Spectrum of 15N16O with the previous available measurements was performed. The global least-square fit provided by far the most complete and the most accurate molecular constants of all the related isotopic species of 15NmO(m=16—18). The accuracy of these constants is improved by 1 or 2 orders. Many of the molecular constants including γ, AD, Δ01, Δ10, Δ00 were determined for the first time.