A new simple layer wise first order theory(LFOT) with two variables was proposed, in which the shear strain was piecewise first order function and integration of it through the laminate thickness could fulfill Timoshenko shear strain theory. The equilibrium equation was derived by minimum energy principle and solved by Rayleigh Ritz method. After comparison with classical first order theory(CFOT) and test results, it has been shown that the predicted value by LFOT is relatively more conservative than CFOT because of considering skin resistance to shear force. Generally, the core shear strain and stress calculated by LFOT is lower than that of CFOT with the same construction and loading level. But difference between the two theories becomes smaller with the increasing core thickness. Furthermore, the shear resultant derived by LFOT fulfils the static equilibrium.