Teaching children to become effective thinkers is increasingly recognized as an immediate goal of education. The purpose of this research was to investigate the effect of Problem Solving as a teaching- learning method that may teach children a set of thinking skills. The sample of the study consisted of 42 preschool children from Damascus city .The sample was divided into experimental and control groups .Means and Standard Deviations were obtained for the two groups and the statistical analysis revealed the following results: 1-Significant differences were found between the averages of the experimental and control groups in which the later group has a lower average according to the thinking skills test 2- Significant differences were found between the averages of the control groups between the first applied test and second applied test , that the averages of the control groups in the second applied test were increased. The findings of the study show the importance of Problem Solving as a good method for improving Kindergarten children’s thinking skills. Children became more active. This study suggested the application of Problem Solving as a teaching - learning method in kindergarten, continuing education courses in teaching thinking skills as a new metho, Reducing numbers of children in the classroom, and highlighting the importance of teaching thinking skills at a very early stage.