1. A moving object detection apparatus using optical flow analysis, comprising: an image capturing module for successively capturing a plurality of images; an image aligning module for obtaining an aligned previous image for each pair of neighboring images of said plurality of images, said pair of neighboring images being called previous image and posterior image respectively, an image matching module for taking a pixel as a unit and obtaining displacement vectors of corresponding pixels of said previous image and said posterior image through optical flow tracing; and a moving object detection module for combining all said corresponding pixel displacement vector of all the pixels in said posterior image to determine the location of said moving object within an image frame.