Abstract: Trifluoroethyl sulfide acaricides have been studied for their novel structures and excellent acaricidal efficacy. To discover new acaricides with high activities, 25 novel trifluoroethyl sulfide compounds containing spirothiazolidinones were designed and synthesized by introducing the spirocyclic fragment of spirocyclic tetronic acid acaricides to the thiazolidinone group based on the lead compound sulfiflumin. 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 VIIh was more effective against T. cinnabarinus with the LC₅₀ value of 4.3 mg/L, which was slightly higher than sulfiflumin (1.1 mg/L) and cyetpyrafen (1.7 mg/L).