The single toxicity of cadmium(Cd) or 9 substituted phenols to Phtobacterium phosphoreum was determined,respectively. The results indicate that the single toxicity was related to group variety, group sum and substitutive positions. On the basis of single toxicity, the joint toxicity of Cd and 9 substituted phenols was measured. The result indicates that the joint toxicity was basically a simple addition of the single toxicity of them or close to simple addition of the single toxicity of them. QSAR equations were built from the joint toxicity and molecular structural descriptors of substituted phenols under the different Cd concentrations. It was shown that the joint toxicity under different Cd concentrations was related to the identical descriptors, the logarithm of n-octanol/water partition coefficient(lgP) and the heat of formation(△Hf), with R2=0.855, 0.878 and 0.780, respectively. Good agreement between the predicted and observed values was found with R2=0.837.