Objective To investigate the distribution features of TCM patterns and differentiation method of thyroid cancer through cluster analysis on data of TCM four examinations after surgery.Methods The data of TCM four examinations were collected from 304 patients by applying cross-section epidemiological survey,and then given quantitative classification and a database was established.The quantitative scores of each patient were given cluster analysis by using sample clustering analysis method (Q clustering) for getting the proportion of each category of four examination information.The preliminary criterion for patterns of thyroid cancer was made according to the proportion of four examinations information and expert survey of Delphi method at earlier stage,which was combined with clinical practice to determine the patterns.Results All 304 patients were clustered into 9 categories indicated by from A1 to A9.The frequency of A1 was 77 cases;A2,7;A3,1;A4,7;A5,105;A6,7;A7,87;A8,11 and A9,2.Based on clinical practice and experts' experiences,A1 and A7,A5 and A6,and A3 and A4 were merged and evaluated respectively as pattern of dual deficiency of qi and yin (164 cases,53.9％),pattern of liver depression and qi stagnation (112 cases,36.8％) and spleen-kidney yang deficiency pattern (8 cases,2.6％).A2 was evaluated as pattern of yin damaged by stasis heat (7 cases,2.3％).The proportions of four examination information of A8 and A9 were disperse and evaluated as other patterns (13 cases,4.4％).Conclusion The distribution of TCM patterns in the patients with thyroid cancer after surgery has its regularity.It is feasible to evaluate TCM patterns with cluster analysis combining with experts' experiences.