The invention provides a modification clay and a clay-high polymer composite. The modification lamellar clay comprises lamellar clay material of which the intercalation is provided with modifier, the modifier has conjugated double bond structure and can produce a free radical after heated. The clay-polymer composite of the invention comprises high polymer substrate and the modification lamellar clay, wherein the modification lamellar clay is dispersed in the high polymer substrate, and at least parts of high polymer substrate are stripped; the modifier produces the free radical during heatingso as to capture the free radical produced when high polymer substrate is thermally cracked or burnt, thus avoiding the phenomenon that the high polymer substrate is further cracked in short time.