This research aims to determine the effect of discovery learning assisted phet media to increase the ability of making a graph of learners. The research method is used classroom action research, which implemented according to four stage, are planning, implementation, observation, and reflection. The subjects research are 30 of senior high school students. The data used  assessment sheets’ achievement of the ability of making a graph. Research shows that the initials that the application of the discovery learning assisted phet media effect in ability of making a graph by learners. Through three cycle of research, can make the conclusion that the achievement ability of making a graph by learners increased from cycle I to cycle III. The average achievement of the ability of making a graph by learners on cycle I is 62%. On cycle II, the average achievement of the ability of making a graph by learners is increasing being 84%. End while, on cycle III, the average achievement of the ability making a graph increased to 96%. The application of learning discovery learning assisted phet media effect on improving the ability to make a graph.