A surveillance camera has a sensing module, a micro-control unit (MCU) and a real-time clock (RTC) unit. The sensing module records original images. The MCU is connected to the sensing module and stores multiple time settings and a smart timer process. The MCU executes the smart timer process to operate the surveillance camera in a color mode, a monochrome mode or an auto mode based on the time settings. In the color mode, the surveillance camera records color images. In the monochrome mode, the surveillance camera records monochrome images. In the auto mode, the surveillance camera selectively records color images and monochrome images based on a variation between light level of the original images and a predetermined light level. Therefore, the surveillance camera can be set to operate in specific mode based on requirements. The surveillance camera is more flexible and convenient than conventional surveillance cameras.