Method and system for judging scaling critical point of circulating cooling water

The invention discloses a method and a system for judging a scaling critical point of circulating cooling water. The method comprises the following steps: 1) respectively measuring chloride ions Cl0, calcium ions Ca0 and total hardness content YD0 in a circulating cooling water inlet water sample; 2) respectively measuring chloride ions Cl1, calcium ions Ca1 and total hardness content YD1 in the circulating cooling water outlet water sample; 3) calculating to obtain a chloride ion concentration ratio NCl, a calcium ion concentration ratio NCa and a total hardness concentration ratio NYD; (4) calculating the difference value C1 = NCl-NCa between the chloride ion concentration ratio NCl and the calcium ion concentration ratio NCa; 5) calculating the difference C2 between the chloride ion concentration ratio NCl and the total hardness concentration ratio NYD, wherein C2 = NCl-NYD; (6) when C1 is smaller than A and C2 is smaller than A, it is judged that the circulating water does not reach the scaling critical p