Abstract: In order to calculate the modulus of elasticity of the nitrided layer for iron-steel materials,aphysical model of composite beam has been proposed.A specimen which was a equal strong beam was used formeasuring modulus of elasticity and residual stress of the nitrided layer.The experimental results showed thatmodulus of elasticity of the nitrided layer was increased 29.2% than matrix and X-ray stress constant K wasincreased 44.4%than matrix.