The eclogites in northern Jiangsu have at least three types:high pressure crustal type (H-type), ultrahigh pressure crustal type (U-type)and mantle type (M-type).The eclogites of H_type were mainly formed in the lower crust through the low-temperature and high-pressure metamorphism of Jinning orogeny. The eclogites of U-type contain micrograined diamond, coesite and pseudocoesite and exhibit tension crack texture and normal or inverse zoning structure. The garnets consist mainly of grossular and the clinopyroxenes comprise chiefly omphacite of high jadeite, formed in the upper mantle under megatemperature and ultrahigh pressure of Indosinian orogeny. The garnets of M-type belong to pyrope mainly formed near the boundary between lithosphere and aesthenosphere under the megatemperature and ultrahigh pressure of Jinning or earlier orogeny.