. Fracture toughness is the ability of a material to resist cracking. In this paper, ASTM E-399 standard procedure is explained in detail. Fracture parameters such as crack length, crack tip opening displacement and fracture toughness of 70 CT (Compact Tension) specimens of M250 grade maraging steel has been determined and verified according to ASTM E-399 standard procedure. The material used for the study is M250 grade maraging steel. It has got high fracture toughness, easy weldability, high structural strength, high ductility and it can be easily machined and forged. Formation of cracks is mainly due to environmental effects, inferior materials, weld defects and design discontinuities.