Abstract: Flame retardants are used to reduce the flammability of polymer materials, improve their performance of self-extinguishing, and prevent flame from spreading. In recent years, organophosphate ester flame retardants (OPEFRs) have been widely used in textiles, however, OPEFRs are more harmful to humans than other flame retardants. Long-term exposure to OPEFRs may cause thyroid disease, liver damage, immune system malfunction, motor nerve damage, and high likelihood of cancer. The daily used clothing, bedclothes and other textiles have the potential risk of OPEFRs exposure, especially the school uniforms, infant clothes and the clothing that contact the body directly. The United States, Unite Kingdom, Germany, Japan and other countries have already established appropriate regulations and standards for the category and dosage of OPEFRs. In this study, an analytical method for the determination of fifteen OPEFRs in textiles based on ultrasonic extraction with supramolecular solvent and ultra-performance liquid chromatography-quadrupole/Orbitrap high-resolution mass spectrometry (UPLC-Q/Orbitrap HRMS) was established. Firstly, the supramolecular solvent was prepared with 1-octanol as amphiphilic substance and tetrahydrofuran as dispersing agent. Then, the supramolecular solvent was used as extraction solvent for ultrasonic extraction of target compounds from textiles. During this process, the key factors, such as the volume of 1-octanol and tetrahydrofuran, amount of supramolecular solvent, and ultrasonic time, were optimized by single factor and response surface design experiments. After ultrasonic extraction, the target analytes were transferred into the supramolecular solvent phase. To enhance the ionization effect, the supramolecular solvent phase was mixed with the same volume of methanol before analysis by UPLC-Q/Orbitrap HRMS. The analytes were separated on an ACQUITY UPLC BEH C18 column (50 mm×2.1 mm×1.7 μm). The mass spectra were collected in the data-dependent acquisition mode for screening and confirmation. The measurement results showed good linearity over their respective concentration ranges with correlation coefficients (r) greater than 0.99. The limits of detection (LODs) and quantitation (LOQs) are 0.8-16 μg/kg and 2.40 μg/kg, respectively. The average recoveries of the fifteen OPEFRs are 81.0%-118.5% with relative standard deviations (RSDs) of 2.06%-9.98% (n=6). This sample pretreatment method is of advantages of rapidness and the ease to operate. The UPLC-Q/Orbitrap HRMS exhibits high sensitivity, repeatability and efficiency. The developed method can lay a theoretical and experimental basis for the detection of OPEFRs in textiles.