The hydrolysis reaction kinetics of 2-thienyl chalcone derivatives $[II]{sim}[V]$ was investigated by ultraviolet spectrophotometery in 20% dioxane-$H_2O$ at $25^{circ}C$ and the structure of these compounds were ascertained by means of ultraviolet, infrared and NMR spectra. The rate equations which were applied over a wide pH range(pH $1.0{sim}13.0$) were obtained. The substituent effects on 2-thienyl chalcone derivatives$[II]{sim}[V]$ were studied, and the hydrolysis were facilitated by electron attracting groups. On the basis of the rate equation, substitutent effect and final product, the plausible hydrolysis reaction mechanism was proposed : At pH $1.0{sim}9.0$, not relevant to the hydrogen ion concentration, neutral $H_2O$ molecule competitvely attacked on the double bond. By contraries, above pH 9.0, it was proportional to concentration of hydroxide ion.