Abstract: The spotting fluid prepared with existent commercial spotting fluid powders can not give a weighted spotting fluid with satisfactory rheology, dynamic stability and emulsion stability and the problem can not be resolved by increasing amount of spotting fluid powder. By adding a small amount of additive YS, the emulsion stability, the dispersion degree of weighting material (barite) in oil and the viscosity of the spotting fluid prepared were enhanced that results in high dynamic stability of the spotting fluid. The experiments showed that the density difference of the lower and the upper portions of the sample aged 80℃, 16 h was greatly reduced. YS additive is cheap and can be purchased easily in market, so this innovation will have good economic efficiency and bright applicable future.