The invention relates to a scale and 
corrosion inhibitor for treating circulating cooling water, which is prepared from the following components in percentage by weight: 10 to 35 percent of 
polyaspartic acid (PASP) or polyepoxysuccinic acid, 10 to 35 percent of 
sodium gluconate, 0.15 to 3 percent of methyl 
benzotriazole, 1 to 5 percent of imidazoline and deionized water. The 
polyaspartic acid (PASP) or the polyepoxysuccinic acid (PESA) with biodegradability serving as a main body is compounded with the deionized water, the methyl 
benzotriazole, the 
sodium gluconate and the imidazoline to form a 
phosphorus-free product; the 
sodium gluconate has good 
synergy with the methyl 
benzotriazole and the imidazoline, so the scale and 
corrosion inhibiting effect is good, and scale formation, 
corrosion and 
bacteria and 
algae propagation of the circulating water can be effectively prevented; and when the 
added mass concentration is 20mg / L, the corrosion rate is 0.0561mm / a. Under the same 
water quality condition, the scale and 
corrosion inhibitor has low adding concentration, low adding quantity and low cost compared with other like products; and the scale and 
corrosion inhibitor is stable at a high temperature, has certain 
chlorine resistance and 
oxidation resistance, can ensure that a 
system has no scale or corrosion or the like, and can be adapt to the 
water quality of various complex severe working conditions.