Abstract: 3D laser scanning is a new measurement technology which can get real 3D spatial data.It has the characteristics of little restriction, high precision and fast speed which has applied engineering widely. The joints on cliff have a great impact on the formation and development of cultural disease. Joint investigation is important on researching disease causes and conservation recommendations. This paper analyzed disease Causes of stone relics and the role of joint, which also discussed application method of 3D laser scanning in cliff stone protection.