The effects of three isomeric alcohols, butan-l-ol, butan-2-ol, and 2-methyl-propan-2-ol, on the phase behavior and physicochemical properties of the pseudoquaternary microemulsion systems alkyl phenol poly(oxyethylene ether) (OP) + butan-1-ol (butan-2-ol, 2-methyl-propan-2-ol) + hexane (heptane, octane) + 0.05 NaCl solution were investigated with an epsilon-beta fishlike phase diagram method. The properties studied include the composition of the interfacial layer A(S), the solubilities of alcohols A(O,W), and the solubilization ability SP* of the microemulsion systems. With the branched chain increasing, the A(S) and A(O,W)) values are in the order: butan-1-ol < butan-2-ol < 2-methyl-propan-2-ol, but the SP* values are in the inverse order. These results were discussed. The effects of oils on the phase behavior and above physicochemical properties were also investigated.