Wenchuan earthquake of magnitude of 8.0 triggered a large amount of rock slope collapse. In Yingxiu, many high magmatite rock slopes collapsed when Wenchuan earthquake struck, which resulted in huge damage. So it is urgent to study the collapse mechanism. This study takes Laohuzui collapse, a typical high slope collapse located at Yingxiu, the Wenchuan earthquake epicenter, as the object of this research. The engineering geological condition was investigated and the physical and mechanical parameters of rockmass and structural plane were determined.