Abstract： Objective The cartilage link protein (CLP) was labeled by125Iodine.Then the labeled CLP was traced in mice.In order to create a simple and easy experimental method,and to get metabolism paramters for study of tumors,cartilage,connective tissue disease and endemic et al.Methods CLP was labeled with125NaI by the chloramine T and was separated with gel and affinity chromatography.The125I-CLP was examined by in vivo biodistribution and metabolism study.Results Radioiodine labelling rate was 89.90%,radiochemical purity was 92.77%,specific activity was 8.13×109 Dpm/μg and maximal binding rate of125I-CLP to hyaluronic acid was 89.23%.Average plasma half life (T1/2) is 1.84 hour. Clearance rate 1.75 ml/hour.Exclusion rate is 10.03 ml/hour. Steady double metabolic pool model is Ct = 2.4986e-0.5635t+3.24e-0.2833t.Conclusions An effective method of 125I-labeling cartilage link protein is esablished.The cartilage link protein may distribute on the body exist in extracellular ligquid.Liver metabolizes it mainly.Experimental method and metabolism paramters were provided for correlative clinical diseases.