The invention relates to a format document key information block registering and extracting method and a format document key information block registering and extracting device. The method comprises the following steps: performing mode definition on a gray image of a format document; constructing an elastic framework according to the position and a tab area of a tab part; determining a candidate set of registering targets of an elastic framework according to the image pixel duty ratio of the tab part; performing coarse registering on the elastic framework according to image features of the tab part, and determining an initial rectangular frame of a value part; performing precise registering on the initial rectangular frame of the value part according to the position of the tab part, and determining a precise rectangular frame of the value part; determining a format document key information block according to the position of the tab part, character attribute information and the precise rectangular frame of the value part. According to the format document key information block registering and extracting method provided by the invention, contents of the precise rectangular frame of the value part can be extracted accurately by constructing the elastic framework and registering repeatedly; unified management of a database is facilitated.