The purpose of this study is to study crowding issue on a high use level area - theme park. By way of computer simulation, different use levels of encounter at three areas are simulated to measure degree of crowding, acceptability, and preference. Subjects are collected from onsite survey and internet survey. Study results show that critical points for crowding at European Garden District are 20 encounters for on-site and 25 encounters for internet; 25 encounters for both one-site and internet, at UFP Roll Coaster District, and 30 encounters for on-site and 40 encounters for internet at Aboriginal Culture District. Based on these results, this study suggests that visual simulation approach is useful in measuring perceived crowding. Furthermore, people tend to accept more encounters at natural and open district than at artificial facility district in theme park.