ZnTe epilayers have been successfully grown on (100) CaAs substrate by hot wall epitaxy (HWE) with Zn reservoir. Optimum growth condition has been determined by a four-crystal rocking curve (FCRC). It was found that Zn partial pressure from h reservoir has a strong influence on the quality of grown films. Under the determined optimum growth condition, ZnTe epitaxial films with thickness of 0.72~24.8${mu}m$ were grown for studying the effect of the thickness on crystalline quality. The FCRC results indicated that the quality of ZnTe films becomes higher rapidly with increase of thickness up to 6${mu}{ extrm}{m}$. The best value of the FWHM of the few crystal rocking curve, 66 arcsec, was obtained on the film with $12{mu}m$ in thickness. Until now, this result shows the best quality of ZnTe/GaAs films in reported.