Effects of different concentration of cobalt on seed germination and some physiological indexes of rice seedling were studied by adopting the culture method of nutrient solution with rice ’Mian 2 You 647’.The results showed that with the increase of cobalt concentration,the germination rate,germination index and vigor index reduced gradually under the condition of rice seed germination.Root length,seedling height,root weight,seedling weight and plant fresh weight appeared a decreasing trend during seedling growth period.Meanwhile,the chlorophyll content declined rapidly,POD activity and MDA content increased gradually.Among them,root length,root weight and chlorophyll content of rice seedlings were significantly inhibited when the lowest concentration of cobalt was 0.03 mmol/L.The seed germination of rice was significantly inhibited,seedling height,seedling weight and plant fresh weight were significantly decreased,POD activity and MDA content were significantly increased when the lowest concentration of cobalt was 0.15 mmol/L.So the concentrations of cobalt in this experiment had different inhibitive effects on seed germination and seedling growth of rice.