2,3-dichloropyridine was synthesized from 3-aminopyridine by substitution and diazotization, which reacted with hydrazine to give 3-chloro-2 (1H)-pyridinone by electrophilic substitution.The resultant can be used in the next reaction without purification. Under the protection of nitrogen，absolute ethanol as solvent, Ethyl 3-chloro-2(1H)-pyridinone hydrazone reacted with diethyl maleate to give 2-(3-chloro-2-pyridinyl)-5-oxo-3-pyrazolidinecarboxylate, the total yield was 48.0%. Structure of the products were confirmed by IR and 1H NMR.The synthesis process was optimized, optimization of the reaction conditions were found as follows (base on 228.57 mmol 3-chloro-2(1H)-pyridinone hydrazone): under no water and oxygen, speed of dropping diethyl maleate was 10s/d , reflux 1h, the yield was 80.1%.