Abstract: The characters quality evaluation is one of the key technologies in developing a teaching aid which is a function of writing on the prescribed format practical system.In this paper，taking four-wire grid letters written exercises for example，it raises a universal and integrated evaluation method on prescribed format written exercises.This method establishes a reference object model and the quality of description words for each character.The evaluation contents consist of scale，location，and so on.Each category sets their own mathematical model of quality assessment and analysis of threshold，through calculating the distance describing the quality of parameters between the reference of compared model and analyzed model.Then threshold is defined and evaluation of the quality is given.Tests show that the evaluation methods and efficiency meet the needs of English language for the four-wire grid writen teaching aids and fulfill automatic counseling.