The handheld multi parameter water quality detector is developed and designed based on the reference standards HJ/T399-2007 "Determination of Chemical Oxygen Demand in Water Quality - Rapid Digestion spectrophotometric method", HJ535-2009 "Determination of Ammonia Nitrogen in Water Quality - Nessler's reagent spectrophotometric method", HJ671-2013 "Determination of Total Phosphorus in Water Quality - Ammonium molybdate spectrophotometric method", and HJ 636-2012 "Determination of Total Nitrogen in Water Quality - Alkaline potassium persulfate digestion ultraviolet spectrophotometric method". It can quickly determine dozens of concentration indicators such as COD, ammonia nitrogen, total phosphorus, and total nitrogen in water bodies. The instrument is equipped with a high-definition color LCD touch screen, Android intelligent operating system, Chinese display interface, Chinese and English keyboards, user-friendly operation, and easier use; Paired with a 6-hole intelligent digestion instrument, it can achieve rapid outdoor detection.