Nowadays, an increasing amount of psychologists and educators find that literature designed for children plays a very important role in a child’s upbringing. A good children’s book not only influences a child’s psychological development, but is also a useful tool for scholars to research children’s psychology, which reflects children’s thinking regarding certain aspects. Astrid Lindgren’s Pippi Longstocking (1957) and Tetsuke Kuroyanagi’s The Little Girl at the Window (1984) undoubtedly are two representative children’s literatures, which were written during a time where the child's perspective in children's literature was not yet an attitude commonly adopted by narrators in novels. The novels illustrate and highlight children's thinking and reasoning abilities, and the characterization appears to draw on children's developmental cognitive theories, describing a child whose cognition ability recalls Jean Piaget's work and ideas. This thesis attempts to analyze Pippi’s and Totto’s thinking and reasoning and how it can illustrate some of Piaget’s theories about children’s drawing and children’s cognitive development. And a further discussion will be going on in this thesis about how Piaget's work might inform and enrich educational practices in accordance with children’s specific needs at different ages and from different cultural backgrounds.