Abstract: To discover new acaricides with high activities, 25 novel thiazolidinones containing trifluoroethyl sulfoxide compounds were designed and synthesized based on the lead compound—spirothiazolidinones containing trifluoroethyl sulfide moiety, which was reported in our previous work. All the designed compounds were characterized by ¹H NMR, ¹³C NMR and HRMS. Acaricidal activity tests showed that some of the designed compounds exhibited more than 90% activity against Tetranychus cinnabarinus and T. urticae at a dosage of 100 mg/L. Notably, compound Ⅲe was effective against T. cinnabarinus with the lethal concentration 50 (LC₅₀) value of 3.8 mg/L, which exhibited higher activity than the lead compound (4.3 mg/L). This compound can serve as a promising candidate for further development as a new generation of high-efficacy acaricid.