A high performance liquid chromatography-tandem mass spectrometry method for the analysis of tristyrylphenol ethoxylates (TSPnEO) was established. The separation effects of TSPnEO in the four liquid chromatography modes, including reversed-phase liquid chromatography column (XBridge C18, 150 mm×2.1 mm, 3.5 μ m), hydrophilic interaction liquid chromatography column (XBridge HILIC, 150 mm×2.1 mm, 3.5 μ m), amide column (XBridge Amide, 150 mm×2.1 mm, 3.5 μ m) and C18 column (XBridge C18, 50 mm×2.1 mm, 5 μ m) combined with silica column (Nova-Pak Silica, 150 mm×2.1 mm, 4 μ m) were investigated. And the separation effects and sensitivity of TSPnEO in four mobile phases, such as 5 mmol/L ammonium acetate aqueous solution-acetonitrile, 0.1% (v/v) formic acid aqueous solution-acetonitrile, water-acetonitrile and water-methanol, and three eluent gradient conditions were optimized too. The ionization behavior of TSPnEO in electrospray ionization (ESI) was also studied. The results showed that in the ESI positive ion mode, the identified adducts were[M+NH4]+, and the distribution characterization was in Poisson-like distribution. The separation of TSPnEO (n=5-18) was achieved via C18 column combined with the silica column and water-acetonitrile as mobile phases according to the degree of ethoxylation.