Fine motor skill, reasoning ability and general knowledge, which were all closely interrelated with later academic performance, have been proved to be reliable indicators of children’s school readiness. Most of previous studies on this domain usually neglected the developmental traits of preschool children’s fine motor and cognition and their interaction while focusing on the prediction of later academic performance from fine motor skills and cognitive abilities. The purpose of this study was to explore the relationship of fine motor skills, reasoning ability, and general knowledge among 4- and 5-year-old children from a developmental perspective and also to explore the role of concentration on the relationship of fine motor skills and these two cognitive abilities. There were two studies. The first study was a cross-sectional study, which explored the development of fine motor skill, reasoning ability, and general knowledge and their relationships among 4-year old, 4.5-year old, 5-year old, and 5.5-year old children. The mediating and moderating effect of concentration on their relationships were also tested. The second study was a longitudinal study, in which children were fallowed up from 4 years old to 5 years old with an interval of 6 months. The developmental trajectories of fine motor, reasoning ability, and general knowledge and their interactions were investigated. The role of concentration in their relationship was also explored from a developmental perspective. Results of the study indicate 1) fine motor skills, reasoning ability, and general knowledge improved significantly during children’s fourth to fifth year of life, and 2) the relationship between fine motor skills and reasoning ability might decrease with age, and 3) the interaction between concentration and fine motor might be bidirectional. Implications of this research include 1) fine motor skill should be taken as an important skill in the preschool education, and 2) the behavior therapies for children’s cognition should be carried out as early as possible, and 3) fine motor skill might be a reliable indicator for early identification of young gifted children.