College of Geo- exploration Science and Technology��Jilin University��Changchun 130026��China

The article takes slope as subject investigated and the precision in occurrence measurement of five methods such as compass��reflectorless Total Station Instrument (TSI)��laser range finder��3D laser scanner and digital photogrammetric workstation are evaluated by adopting theory of errors �� The root- mean- squrare (��MS) er- rors of trend and dip angle in compass occurrence measurement are ±4°and ±3°��respectively�� The precision e- valuation not only increases the cognition on the precision of compass occurrence measurement but also provides checking calculation data for the precision evaluation of the other four non- contact occurrence measurement meth- ods�� The compass can only be used to measure the occurrence of the underneath discontinuity on high steep slope�� It is range- limited��energy- intensive and ineffective�� The non- contact methods can measure the upper discontinuity on high steep slope which is difficult for people to reach�� The methods using 3D laser scanner and digital close- range photogrammetry can obtain occurrence information of massive stochastic discontinuity on rock mass slope and provide important basic data for the evaluation of slope stability based on stochastic dynamics��