Abstract: The definition and different expressions of safety factor in stability analysis of geotechnical engineering are discussed, and the regulation of distinction between load and resistance in the stability analysis are pointed out. In the stability analysis in geotechnical engineering, the buoyancy of rock mass and structures under static water level shall have the same status of their gravity. The calculated results by use of water pressures on their surfaces have to be equal to those by use of deducting buoyancy. For the saturated soil mass in seepage field, the calculated results by use of the water pressures have to be equal to those by use of considering buoyancy and seepage force on soil skeleton. In the stability analysis, the forces or moments as the loads should have greater weight, thus some reverse forces and moments with little uncertainty will be treated as negative loads rather than the positive resistances. Accordingly, the load and resistance can be defined well provided that safety factor is expressed as the strength reduction factor in the analysis of stability against sliding.