This research explores the desorption mechanism and thermal stability of octadecyl trichlorosilane (OTS, CH₃(CH₂)₁₇SiCl₃) coating on quartz slides and in alkali-metal vapor cells. We measured systematically the morphological thermal-changes, energy dissipation diversity and anti-relaxation characteristic of OTS coatings before and after exposure to Cs atoms by Fourier transform infrared spectroscopy (FTIR), water contact angle measurement, atomic force microscopy (AFM) imaging, collision energy dissipation analysis, and free induction decay (FID) of Cs atoms. The results show that the OTS coatings exhibit the best thermal stability under the specific process conditions, and the homogeneous and dense structure makes the adsorption of alkali metal atoms more stable, which effectively reduces surface energy dissipation and prolongs the relaxation time of Cs atoms. The study provides certain reference for efficient anti-relaxation coating fabrication and coated cell application.