Rapid detection of unsymmetrical dimethylhydrazine （UDMH） and its transformation products in water is of great significance for its pollution control. This paper reviewsthe research progress of chromatographic methods （including gas chromatography， high performance liquid chromatography， and ion chromatography） and non-chromatographic methods （including the electrochemical method， spectrophotometry and chemiluminescence） in the detection of UDMH in water. Then， application of chromatography in in the detection of UDMH conversion products in water was briefly introduced. The advantages and disadvantages of different detection methods in the detection concentration range， sample pretreatment and anti-interference ability， etc.，were pointed out. It was suggested that the design of efficient automatic chromatographic pretreatment device and the combination of various separation and detection technologies would be the future development direction to solve the detection problem of UDMH and its transformation products in water.