Cleaning agent for circulating water on-line monitoring system, and preparation method and cleaning method thereof

The invention discloses a circulating water on-line monitoring system cleaning agent, a preparation method thereof and a cleaning method. The circulating water on-line monitoring system cleaning agent comprises the following components in parts by mass: 1-3 parts of sodium citrate or sodium ethylene diamine tetracetate; 0.2 to 0.5 part of polysorbate-20 or fatty acid sorbitan 80; 2-5 parts of sodium chloride; and 1-3 parts of sodium polyphosphate. The cleaning agent provided by the invention fully considers the component condition of the sediments in the circulating water online monitoring system, does not contain strong acid and strong alkali, is a mild cleaning agent, avoids corrosion and influence on a detection element and an optical element, and protects the online monitoring system while cleaning the sediments. The concentration of a cleaning agent used in the cleaning process is low, the cleaning time is short, the residual amount of the cleaning agent is low, and the requirement for short-term and lon