Nanocrystalline tungsten doped zinc oxide (Zn1-xWxO where, x=0.01, 0.02, 0.04, 0.06) was synthesized by the sal-gel method. the bright and dark field modes of TEM have been used to characterize the grains and sub grains of nanopowders, respectively. The planar defects of samples were studied by using the DiffaX software. To do this, the X-ray diffraction patterns at different twinning and stacking faults probability were simulated. The Williamson-Hall plot of simulated patterns were compared with those extracted from W-doped samples. It was found that among the various compressive and tensile twins, only the behavior of broadening in {11.1} <(1) over bar(1) over bar .6 > tensile twins is similar to Williamson-Hall plot of doped samples. The results of DiffaX simulation were incorporated into the eCMWP fitting procedure and the impact of microstructure parameters including crystallite size, size distribution function, twin boundary frequency, dislocation density and outer cut-off radius of dislocation were studied as a function of W doping concentration.