A testing device for testing read performance of a disc drive, includes a receiving unit, a cache and a detecting unit. The receiving unit receives images obtained by the disc drive. The cache temporarily stores the received images. The detecting unit detects the number of the images in the cache and generates a detecting signal to indicate that there is an abnormity if the number of the images in the cache is less than a preset value. A test method for testing read performance of disc drive is also provided.