This study investigates lateral crustal thickness changes in Turkey by 2-D ML Shear Wave Velocity Tomography technique. In this research the data bank collected from KOERI network, Observatories and Research Facilities for European Seismology and Iranian Seismic network. The data set consists of 25691 amplitude velocity measurements from 521 of event. Using a constrained least-square inversion scheme, 2-D ML Shear Wave Velocity Tomography map is obtained. Eastern of Turkey and Anatolide block in southwest of turkey have velocities greater than 4 km/s indicating obstacle regions for Lg wave. Kirshehir block in central Anatolia shows low Lg velocity due to being continental crust. Pontides terrain in the north of northern Anatolian fault zone has a velocity equal to Lg group wave velocity. In the west of turkey, south of Marmara see low velocity is obtained.