Systematic local structural studies of Ba_1-xK_xFe_2As_2 system are undertaken at room temperature using atomic pair distribution function (PDF) analysis. The local structure of the Ba_1-xK_xFe_2As_2 is found to be well described by the long-range structure extracted from the diffraction experiments, but with anisotropic atomic vibrations of the constituent atoms (U_11 = U_22 U_33). The crystal unit cell parameters, the FeAs_4 tetrahedral angle and the pnictogen height above the Fe-plane are

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... n to show systematic evolution with K doping, underlining the importance of the structural changes, in addition to the charge doping, in determining the properties of Ba_1-xK_xFe_2As_2.