Based on a comprehensive sample of seasoned equity offerings (SEOs) in the US for the period 2005 - 2017, this paper focuses on the impact of firm complexity on seasoned equity offerings method. The results from multinomial regression model show that firms with high complexity tend to avoid accelerated offerings but incline to employ firm commitment, private placement, or rights offerings. In these firms, information asymmetry will be higher, and information transparency will be lower; So investors need more time to research and make decisions. Therefore, the methods of firm commitment, private placement, and rights offerings are preferred. In contrast, firms with a lower complexity tend to choose accelerated offerings method, which helps firm raise capital quickly, save time and lower underwriting spreads and fees.