This standard specifies a method for the determination of hydrazine content in water using p-dimethylaminobenzene formaldehyde Spectrophotometric method, spec-trophotometry, which is suitable for the detection of hydrazine in surface water and industrial wastewater. The detection limit of this method is 0.002 mg/L, and the determination range is 0.002 to 1.00 mg/L. When there are interfering substances such as aminourea, thiocyanic acid or urea in the water sample, the measurement results may be affected. The implementation of this standard can provide an important basis for monitoring the environment and industrial wastewater management, especially when it is important to detect the potential impact of industrial emissions on the environment.