Abstract: The data of this paper was gathered from 880 cases in Liaoning province in China. By applying the Theory of Quantification Type I and the Multiple Stepwise Regression the mathematic models were established to estimate age on the basis of the tooth attrition-degree, and the equations on the estimation age of different age groups have been obtained by the aid of computer tech- nique as well. These equations, for the convenience of usage, have been turned into the tables on estimation of age. The correlation coefficients (R) are from 0. 61 to 0. 83. The test-significance of variance analysis is of greet sig- nificance (F>F0. 01). The errors of the estimated age with the real age is as follows; 57. 3-96. 3% in ± 3 years error, 77. 3-100% in ±5 years error.