The impact of Information Technology on human life affects early childhood education. From the computer-assisted instruction to the exercise of multi-media in worldwide web, and to the Information Technology Integrated Instructions, young children's learning is increasingly developing with the innovations of Information Technology. With the DAP principle in NAEYC, the curriculum design for young children needs to meet children's learning and development, to know what is individually appropriate and to know what is culturally important. Hence, the aim of the study is to investigate the effects of preschool teachers' teaching belief on teaching effectiveness from the aspect of Information Technology Integrated Instructions. With random sampling to distribute and collect questionnaires on-site, 550 preschool teachers who are teaching for 5-year-old children in Chiayi, Kaohsiung, Tainan, and Pintung are selected as the research subjects. Within the collected 402 copies, 34 invalid ones are deducted. Total 368 valid questionnaires are retrieved, with the retrieval rate 67%. With SPSS, Factor Analysis, Regression Analysis, and Hierarchical Regression Analysis are utilized for data analyses. The research outcomes are concluded as follows. (1) Teaching Belief is partially positively related to Teaching Effectiveness. (2) Information Technology appears partially positively related to Teaching Belief. (3) Information Technology reveals partially positively related to Teaching Effectiveness. (4) Information Technology shows partially significant moderating effects between Teaching Belief and Teaching Effectiveness. Based on the research outcomes, it is expected to provide early childhood educators some suggestions and reference in Information Technology Integrated Instructions and Teaching Effectiveness. (author abstract)