In this paper, the surfactivities of the water extraction of the Sapindus saponin from the pericarp of Sapindus mukorossi, its fermentation product, and the mixture of the fermentation product and other four surfactants were studied. Our results showed that, compared with the water extract, the stability at high temperature, lower critical micelle concentration(cmc) and surface tension(γcmc), foaming and emulsifying capability of the fermentation product were impoved in some degree. Based on Rosen theory, the binary mixture systems contained the fermentation product of Sapindus saponin and one of the follwing surfactants, Sodium alcohol ether sulphate(AES), Octadearyl dimethyl ammonium chloride(1831), Alkyl polyglycoside(APG), or Pepega, were constructured, and then their surfactivities were determined. According to the cmc, γcmc and foaming ability tests, they showed synergistic effects in different degree.In emulsifying ability test, a remarkable synergistic effect exsited in the mixture of the fermentation product/APG both on palm oil and liquid paraffin, while there were synergistic effects only on palm oil in the other three mixtures, not on liquid paraffin.