The invention discloses an online detecting method of the content of heavy
metal in water. The online detecting method comprises the following steps: sucking an original
water sample of a river channel into a storage cabin by a sampling device, and switching off a water
inlet valve and switching on a water outlet valve when a
liquid level sensor in the storage cabin induces that the
water sample reaches a set amount; outputting the original
water sample from the storage cabin, forming a dosing water sample after mixing the original water with a
reagent, feeding the dosing water sample into a
digestion device, digesting in the
digestion device, and cooling; opening a detection
light source of a
detector, irradiating the dosing water sample by the detection
light source through the digestiondevice, reading an optical
signal from the
detector, and computing the content of the heavy
metal; sending data to a computer side by the
detector through a
wireless signal, and saving the data, thusrealizing real-time online monitoring on the content of the heavy
metal in the water. According to the online detecting method disclosed by the invention, 24-hour real-time automatic online detectionon the heavy metal in the water can be realized, and the detection accuracy is high; a detection process is simple and easy to realize, an operator is not required to be on the scene all the time, and labor strength is reduced.