Abstract: The jointed rock is supposed to be composed of a homogeneous macrostructure and a heterogeneous periodic microstructure. Based on the homogenization method, the equivalent elastic modulus of jointed rock is studied. Using the periodicity assumption and asymptotic expansion of the displacement, the micro governing equation concerned with microstructure of jointed rock is derived by perturbation method. Finite-element-method numerical analysis is carried out for solving two dimensional rock materials. The numerical results of equivalent elastic modulus are compared with those obtained by Taylor method and self-consistent method as well as Hashin-Shtrikman bounds so as to verify the rationality of the homogenized method. The relationship between the elastic properties and the constituent properties of the rocks are examined, also the influence of Poisson ratio on the equivalent modulus of jointed rock is analyzed.