Abstract: This research aimed at the investigation of the main factors that influence children' s cognition of geometric figures of rectangle, triangle, trapezium, ellipse and parallelogram. We chose object factors, inner-category and outer-category as interference factor and name, indication. classification, confirmation to distinguish five test items. Our research results indicated that the important criteria of children is elementary geometric cognitive development is casting off the nonessential feathers, confirming the varied figures and distinguishing the outer-category similar figures. Adopting double classification standards and separating the essential from nonessential feathers are the main transition status of the development of children' s ability to classify geometric figures. Language prompt play an important role in classifying. Especially, the elementary geometric knowledge of second grade primary school pupils merely correspond to the level of five year old children, therefore, the educational department concemed should pay great attention to this phenomenon.

Key words: elementary geometric knowledge, double standards, inner-category interference, outer-category interference, distinguish, confirmation