Experiment has a very important role in physics, because a scientific phenomenon could be investigated and understood through it. Photoelectric effect is a phenomenon that explains the nature of light and the fundamental of quantum mechanics. The lower cognitive level of undergraduate students about photoelectric effect is caused by the limitation of apparatus in the real laboratory.  This study describes the exploration of photoelectric effect simulation on PhET virtual laboratory (Physics Education Technology) about factors that influence the amount of emitted electrons in photoelectric effect. The investigated variables are voltage, metal material, light intensity, and light wavelength. Current is used to indicate the amount of emitted electrons. Those are accommodated in photoelectric effect simulation on PhET so that four experiments could be done i.e. : the effect of voltage to current, the effect of metal material to current, the effect of light intensity to current, the effect of light wavelength to current. Based on the exploration of PhET simulation, the result was factors that influence the amount of emitted electrons in photoelectric effect are metal material, light intensity, and light wavelength. This is consistent to references. Thus, photoelectric effect simulation on PhET can be used as physics learning media to investigate factors that influence the amount of emitted electrons in photoelectric effect.