During the epidemic, online advertising became more important, and several studies have suggested that internet users tend to avoid viewing online ads, such as banner ads. Previous studies have shown that product items that use animation lead to increased visual attention to all items on a webpage at the expense of attention to nonanimated items on the same webpage. However, few studies have compared the impact of the picture and text forms taken by static banners on the effectiveness of banner ads. At the same time, whether semantic factors (theme consistency) moderate the influence of structural factors (picture and text forms) on banner advertising remains unknown. The aim of this paper is to examine the influence of structural factors and semantic factors of ads on participants' visual attention to and memory of banner ads. The participants (twenty-seven males and forty females aged 18-26 years) were divided into two groups, one for consistent ad-web content themes and the other for inconsistent ad-web content themes. Then, the participants were asked to browse 16 complete pages (4 pages each of text-type web content and text-type banner ads, picture-type web content and picture-type banner ads, text-type web content and picture-type banner ads, and picture-type web content and text-type banner ads), and their eye movements were recorded to measure the participants' level of attention to the banner ads. A recognition task was used to measure the participants' memories of the banner ads. The results showed that the text-type banner ad had a lower blindness rate and exerted better attention and memory effects than the picture-type banner ad, and the text-type banner ad had a lower blindness rate and better attention and memory effects when positioned in the background of picture-type web content than when positioned in the background of text-type web content. A significant interaction effect among banner ad type, web content type and theme consistency showed that ad-web content theme consistency moderated the effect of web content type and banner ad type on ad effectiveness. Taken together, the results of these tasks demonstrate that theme consistency moderates the effect of web content type and banner ad type on ad effectiveness in a top-down manner. To reduce the negative effect of banner blindness, placing text-type banner ads in picture-type web content and setting a consistent theme between the banner ad and the web content is the more effective choice. The findings from this study can be used to assist advertising agencies in designing more effective and efficient banner ads from the perspective of basic psychology.