A method maintaining an image background by multiple Gaussian models utilized to a device includes the following steps. First, the device captures an image frame having pixels to obtain background information, and then calculates the background information to establish a primary Gaussian model. Next, the device captures continuous image frames in a time period to obtain and calculate graphic information for establishing a secondary Gaussian model, and then repeates the steps to establish multiple secondary Gaussian models. Finally, the device compares two secondary Gaussian models, and then updates learning for the primary Gaussian model by the secondary Gaussian model if the graphic information of the secondary Gaussian models are attributable to the background information, or maintains the background information of the primary Gaussian model without updating the learning if anyone of the graphic information of the two secondary Gaussian models is unattributable to the background information.