The sports lottery industry is growing globally, especially in the online betting market. This study focuses on online sports lottery behavior and tries to propose a framework applied in a virtual environment. Based on the Technology Acceptance Model, four antecedes (subject norm, computer anxiety, computer self-efficacy, and personal innovativeness) are added to this framework. The subjects of this study, from whom 268 valid questionnaires were collected, were betting members of sports lottery venders in the Taichung district. Findings show that subject norm is a good antecede in this framework, but computer anxiety does not reach statistical significance for explanation in this study. Both computer self-efficacy and personal innovativeness positively influence perceived usefulness. The results demonstrate the value of the expanded TAM and use of the expanded model indicates a high degree of acceptance for online betting systems among sports lottery consumers. The TAM expansion proved relevant in gathering applied information on the behavior of sports lottery consumers.