The pilot study was conducted to exploit the development of the shape conservation and illusory contours for children. The single-subject design selected 11 children (2 to 12 years old) on purpose. Each anticipant observed objects' turning and analyzed by percentage and descriptive statistics. According to the result of analysis, four conclusions were obtained: 1) it showed differences for 2-12 years old children to naming but general situation of verbal error. 2) 2-12 years old children observed and found the illusory contours. 3) it showed differences among ages and experiences for children to explain and definite illusory contours. 4) it also showed differences among ages and experiences for children of the shape conservation. Via the findings of this study the author dared recommend some suggestions to advance future research about learning and cognition for children.