Abstract: Due to the characteristics like high and steep slope and its strong concealment, the accurate identification of dangerous rocks in high and steep slope has always been confronting with great difficulty. The author uses technology like unmanned aerial vehicle aerial photography and Agisoft PhotoScan to establish the dioramas and three-dimentional data of the rock mass in high and steep slopes. Based on the principle that three points which are non-collinear can specify a plane, the author uses Visual Basic language to write a program in order to complete the calculation of structual plane's occurrence, thereby a algorithm is formed to accurately indetify the structual plane of rock mass and massively and rapidly extract point cloud data to calclulate the geometrical characteristics of structual plane's occurrence. And a typical rock mass slope in Zhejiang Immortals scenery area is selected as a case to analyze. After confirming the dangerous rocks, the motion features of the unstable rocks are predicted and analyzed with the assist of rolling rocks simulation software. The results show that once stones fall from A-D they will all hit directly in travel line, therefore cause great threaten to the security of travelers. It is advisable to take engineering measures as soon as possible to reduce risk levels.