Abstract: In the approximation of the modulation process of two scale-eddies (inner-scale and outer-scale eddies) for light wave propagation in turbulent atmosphere,we study the wave structure function(WSF) used to calculate the mutual coherence function from which the transverse coherence length can readily be determined for an infinite plane wave or spherical wave.Analytical expressions are derived by means of the development of the modulation model of the power spectral density of the refractive-index fluctuations which include the factor of small-scale and large-scale sizes turbulence eddies for the wave structure function associated with the propagation of infinite plane waves and spherical waves through isotropic and homogeneous turbulence.For computational case,the approximation expressions for the structure function of infinite plane waves and spherical waves propagating through isotropic and homogeneous turbulence are also developed by simple interpolation method,whose error is less than 2%.