Abstract: Objective To detect and analyse CRP level in rats chronic periodontal and atherosclerosis compound model. Methods 60 rats were randomly divided into four groups, each group 15: Group A:control group; Group B:periodontitis group; Group C:atherosclerosis group;Group D:periodontitis and atherosclerosis group. Every group accepts the corresponding treatment. Observe pathological changes in periodontal tissue of experimental teeth and arterial vessels. CRP level in serum were assayed by ELISA. Results Histopathology Observation of periodontal tissue revealed: Obvious inflammation of periodontal tissue were observed in group B,D. Attachment loss level in group B and D were higher than that of A, C groups(P <0.05). Histopathology Observation of arteries revealed: tunica media of artery thickening in group B. Thoracic aorta, abdominal aorta atherosclerotic lesions formationed in group C,D. Serum levels of CRP in group D were higher than other groups (P <0.05). Dependablity analyse revealed: CRP and AL in both group B and D were positive correlation. Conclusion Atherosclerosis and periodontitis could influence each other,the development of two diseases may concerned with serum levels of CRP.