The aim of the current research was to investing the effectiveness of using the six dimensional PDEODE strategy in developing the geometrical proof skills for the preparatory stage student. To achieve this goal, a geometrical proof skills test was constructed. The research was limited to a sample of second grade students in preparatory stage, and was divided into two groups, one experimental from meit fares middle intermediate school and the other controlling from Alghuri school of basic education, Berket Al-Sabaa, Menoufia.Using the quantitative statistical analysis methods, the crude scores of the research sample (60 students) were analyzed. The result of this analysis was that: there is statistically significant difference at the level (0.05) between the average scores of the students in the experimental and control groups on overall geometrical proof skills test and sub-skills (proof planning, proof thinking, proof formulation, proof evaluation) separately for the students in the experimental group.From the previous results, some suggestion and re commendations were presented the following: the six dimensional PDEODE strategy should be applied to the teaching of geometry to students at the preparatory stage, given the pleasant atmosphere it provides during the courses of learning, since it depart from the traditional way of teaching which increases the motivation to learn geometry, also increases students' active participation in learning.