Objectives:To observe the changes of the tongues in rats with blood-stasis syndrome induced mainly by cold.To explore the evidence that tongues were the target of blood stasis syndrome and the target of medication.Methods: Rats with blood-stasis syndrome induced by cold（BSC group） were dipped into ice water（0 ℃） for 5 minutes every day and lasted 20d individually.Different drugs were given orally after the model establishment.And then we took photos of tongues of all rats by digital camera

analyzed the gray scale value of all rats’ tongues using image analysis software

and observed the capillaries in tongues by electron microscope.Results: The tongues of rats which had been frozen in ice water for 20 d（once a day） were dark purple

the same as that of models induced by chemical materials.While as for the normal rats

the tongues were lustrous and ruddy.The changes of color of the tongues persisted about 1 week and were great obvious at the 3rd day after the model establishment among different time-points.After given different drugs

the degree of dark purple tongue degraded

showed significant difference（P<0.01） from that of model rats.The capillary stegnosis and nucleus turgescence of vascular endothelial cell were observed in tongues in BSC group by using electron microscope.After medication

the above changes recovered.Conclusion:The degree of dark purple tongue indicates the degree of diseases with blood-stasis syndrome.The tongue probably is a target of drug treatment.