The article reports the effect of Yin and Qi tonifying herbs (Radix Rehmanniae, Radix Ophiopogonis and Pseudostellaria Heterophylla) on hyperthyroid model of Yin-deficient rats. The model rats were made Yin-deficient by injecting thyroxine. Observation showed that after injection, indexes such as anus temperature, oxygen consumption, weight, diet, activity, general conditions, triiodothyronine (T3) and thyroxine (T4) in serum were markedly changed. It is thus suggested that the Yin and Qi tonifying mixture of the above three herbs can regulate and correct Yin-deficiency in hyperthyroid model of Yin-deficient rats.