 The purposes of this research were 1) to develop mathematics learning plans on geometric transformation by using GSP for Mathayomsuksa two students to meet the effectiveness criterion at 80/80 2) to compare students&#8217; achievement before and after studying by using the learning plans and  3) to study the students&#8217; attitude toward the learning plans.
                The samples were 30 students of Mathayomsuksa two in the second semester of the academic year 2008 at Watbangwua (Saisermwit) school in Bangpakong District, Chachoengsao Province. The research instruments were the mathematics learning plans on geometric transformation by using GSP, an achievement test and an attitude test.
              The results of the research were as follows: 1) the effectiveness of mathematics learning plans on geometric transformation by using GSP was 88.49/83.48  2) the students&#8217; achievement on studying by using the learning plans was higher than before with statistical significant level .01 and  3) the students&#8217; attitude toward learning by using GSP was a highest level.
