The effects of rare-earth elements on physiological and biochemical responses of wheat under acid rain stress were studied by pot experiments. The results showed that the stress of acid rain resulted in the decrease of chlorophyll content and the change of chlorophyll a/b values. Chlorophyll a and chlorophyll content were positively correlated with the pH value of acid rain and the peroxidase activity increased gradually with decreasing pH value. The effects led to the increased decomposition of chlorophyll and decreased content and a/b values of chlorophyll, which reulted in a speed-up blade decay and the defect of absorption and transformation of light energy and metabolism of carbohydrates. Under lower acidic conditions, the rare-earth elements can protect wheat from being damaged by acid rain and affect chlotophyll metabolism and peroxidase activity of wheat.