Abstract: With an appropriate observation distance of 20～30 mm, industrial video endoscopesare used to observe the dead zones which can't be detected with penetrant testing. Compared with visual observation, the sensitivity reduces but the results can meet the testing requirements. In addition, the effects of surface treatment are also investigated by a serious of contrast experiments before and after the penetrant testing. The blasting and pickling surface treatments can improve testing background and the defects opening can fully be exposed to the surface by pickling. The titanium castings shall be treated by blasting and pickling before the penetrant testing, and the dehydrogenation is also needed timely.