1. A pedestrian tracking and counting method for a near-front top-view monitoring video, comprising: acquiring a video image under a current monitoring scene; comparing the video image with a background image, and when it is determined that the video image is a foreground image, segmenting and combining each blob in the foreground image to acquire a target blob representing an individual pedestrian; performing tracking and counting according to a centre-of-mass coordinate of each target blob in a detection area to acquire the number of pedestrians under the current monitoring scene, wherein segmenting each blob in the foreground image comprises: segmenting a blob having a width of a circumscribed rectangle of the blob greater than twice a threshold T W of a width of an individual by equal width according to T W ; segmenting a blob having a height of a circumscribed rectangle of the blob greater than twice a threshold T H of a height of an individual by equal height according to T H ; deleting a blob having an area smaller than a predetermined threshold, wherein the blob is acquired after the segmenting.