In order to easily synthesize sodium pentazolate， the synthesis method and conditions of sodium pentazolate were studied. Diazoniums 4a-b and sodium pentazolate were characterized by infrared （IR）， nuclear magnetic resonance （NMR）， mass spectrometry （ESI-MS）， or ion chromatography （IC）. Results show that sodium pentazolate can be easily synthesized via the cyclization/C—N cleavage one-pot method； the appropriate reaction conditions for the synthesis of sodium pentazolates from diazonium chloride 4a are as follows： the molar ratio of NaHCO₃ to 2，6-dimethyl-4-aminophenol is 0.6， the cyclization temperature is -45 ℃， the cyclization time is 2 h， the C—N cleavage temperature is -35 ℃， the C—N cleavage reaction time is 24 h， and the molar ratio of m-CPBA to 2，6-dimethyl-4-aminophenol is 3∶1； the suitable reaction conditions for synthesizing sodium pentazolate from diazonium tetrafluoroborate 4b are as follows： the molar ratio of NaHCO₃ to diazonium tetrafluoroborate is 0.3， the cyclization temperature is -45 ℃， the cyclization time is 7 h， the C—N cleavage temperature is -35 ℃， the C—N cleavage reaction time is 24 h， and the molar ratio of m-CPBA to diazonium tetrafluoroborate is 4∶1； sodium pentazolate can be easily isolated by ethanol extraction， of which the purity is up to 98.87 % （area normalization）.