Abstract: Synthesis of p-chlorophenylpropiolylamides and itsreaction produets with hydrazine hydrate were studied. It was found that the reaction products varied with the different Substituent groups in the amidel When the substituent group was isopropyl or sec-butyl group, p-chloro-β-hydrazino-cinnamamides (Ⅱ) were obtained. Under similar reaction conditions, when the substituent, group was n-propyl, n-butyl or diethyl group, cyclization reaction occurred and the reaction product was 3-(p-chlorophenyl)-pyrazol-5-one (Ⅲ). All the compounds were tested in mice for anticonvulsant activity. Prelimary data showed that p-chlorophenyl-propiolyl-sec-butylamide (I₄) and p-chlorophenyl-propiolyl-n-propylamide (I₁) exhibited moderate anticonvulsant activity. The ED₅₀ was 54.5(34.4～86.4), and 56.1(31.6～99.6) mg/kg respectively. The compounds of p-chloro-β-hydrazino-cinnamamide (Ⅱ)and 3-(p-chlorophenyl)-pyrazol-5-one (Ⅲ) showed no significant effect on antieonvulsant activity. p-Chloro-cinnamoyl-hydrazide (Ⅳ) provided good anticonvulsant activity.