An image testing method of an image pickup device and an image testing apparatus using such a method are provided. The image testing apparatus is in communication with the image pickup device. The image testing apparatus includes an image processing program, a multi-core processing unit and a storage unit. The image processing program is used for segmenting the main image, which is acquired by the image pickup device, into plural sub-image blocks, and transmitting the sub-image blocks to respective threads. The multi-core processing unit is used for synchronously executing the threads, thereby synchronously analyzing imaging quality of respective sub-image blocks. The storage unit is used for storing analyzing results of respective sub-image blocks. The analyzing results of respective sub-image blocks stored in the storage unit are combined together by the multi-core processing unit, thereby acquiring the imaging quality of the main image.