To prevent severe pollution of inorganic snowmelting agents on greenery along urban roads, half lethal dose (LD50) of plant population was confirmed through stress simulation of chloride snowmelting agent on Euonymus japonicus, plant physiological change analysis, plant population lethality rate statistic and mathematic modeling analysis within a 30day subacute toxicity test. Results indicated that a significant positive correlation in the early stage and a significant negative correlation in the later stage were observed between the total content of chlorophyll a and b in plants and cumulative dose of chloride snowmelting agent. The free Lproline content in plants and the dose of snowmelting agent were positively correlated during the whole period. No significant correlation in the initial stage, but a significant negative correlation in the later stage was observed between the soluble protein and the dose of snowmelting agent. The LD50 of chloride snowmelting agent on E. japonicus is 5 kg/(L•m2) within a 30-day period.