Motivated by the outbreak of COVID-19, museums have increased interests in online museum and online museum education. This study presents a way to use AI image synthesis technology for online art education guided by a constructivist design approach. An experiment was conducted to empirically test the effectiveness of AI-based art education in the online museum context. A total of 83 participants visited one of 3 different web-based art museums (i.e., AI image synthesis not applied vs. AI image synthesis applied with given photos vs. AI image synthesis applied with self-uploaded photos). Those who experienced the online museum with synthesized images using self-uploaded photos reported a higher level of motivation and satisfaction and to experience in a more constructivist way compared to other conditions.