Objective To establish an osteosarcoma model of rat and to study its biological characteristics.Methods Intact tumor pieces were inoculated into the right tibia of rat,the rats were killed in different time and observed the growth of tumor and metastasis.At the same time,serum alkaline phosphatase was detected.Result The tumor growth rate was 91.67%,from the first week to the second week,the tumor grew out from medullary cavity,then it widely destroyed cortical bone and invaded soft tissue on third week but there was no pulmonary metastasis.Pulmonary metastasis took place on the fourth week,on the fifth week the cortical bone was destroyed more obviously than before and the quantity of pulmonary metastasis increased,and the rat finally died for respiratory failure on the sixth or seventh week.The level of ALP began to step up from the first week to the second week,reached a peak on the third week.It fell off from the fourth week to the sixth week,and approached a platform on the seventh week which was still higher than normal level of same time.Conclusion The tumor growth rate is high,and the animal is available easily.So the model can be widely used for scientific research.The model simulated the clinical process of human osteosarcoma,and could be a satisfactory model for studying osteosarcoma.