A testing apparatus for testing delay characteristics of a multimedia player in an enclosed environment includes a storage device, a controller, a recording device, and a processor. The controller controls the multimedia player to display a video having a number of different scenes with different brightness and sends a switching instruction to switch the scenes. The recording device records a number of ambient light intensities in a darkroom at predetermined time intervals. A testing system executed by the processor compares two adjacent ambient light intensities to determine the actual switching time between the scenes and evaluates the delay characteristic according to differences between the actual switching times and a transmitting time of the instructions to switch.