Octylphenol polyoxyethylene ether (OP-20) and sodium dodecyl sulfate (SDS) are commonly used surfactants in the later stage of oilfield exploitation. In order to accurately detect the content of each component in OP-20/SDS binary complex system, hydroxypropyl-β-cyclodextrin (HP-β-CD) was used as a masking agent to modify the UV spectroscopy and then detect the content of OP-20 in binary complex system by using its special structure of external hydrophilicity and internal hydrophobicity, as well as the characteristics of spontaneous inclusion of aromatic surfactants. At the same time, the conductivity method was used to quantitatively analyze the SDS in binary complex system, and then the effect of OP-20 on the test results was studied. The results showed that SDS could interfere with the absorbance and critical micelle concentration（c_cmc）of OP-20 when the content of OP-20 in binary complex system was detected by UV spectroscopy. When 0.4 mmol/L SDS was added to 0.2 mmol/L OP-20 aqueous solution, the absorbance of OP-20 at the maximum absorption wavelength of 224 nm increased from 1.727 to 1.751. In 0.4 mmol/L SDS aqueous solution, the c_cmcof OP-20 decreased from 0.223 mmol/L in pure water to 0.198 mmol/L. HP-β-CD had a significant masking effect on the detection of OP-20 in binary complex system by UV spectroscopy. HP-β-CD and OP-20 were encapsulated at a molar ratio of 1∶1, which blocked the mutual interference between OP-20 molecules and SDS molecules. After adding HP-β-CD, the recovery rate of OP-20 in binary complex system changed from 96.42%—106.92% to 99.28%—101.38% . As a result, the accuracy of detecting OP-20 content in complex system by UV spectroscopy was significantly improved. The reason why HP-β-CD eliminated the mutual interference between SDS and OP-20 was that OP-20 molecules entered the HP-β-CD molecular cavity from both wide and narrow aperture directions and then formed an inclusion complex. The conductivity method could accurately detect the content of SDS in binary complex system, while OP-20 would not interfere with SDS. When the concentration of OP-20 in the solution was 0.1—0.3 mmol/L, the recovery rate of SDS in binary complex system was 100.83%—101.92%. HP-β-CD modified UV spectroscopy combined with conductivity method could effectively detect the content of each component in OP-20/SDS binary surfactant system.