Abstract: According to the extremely abundant genetic indicators of the Palaeogene extra-thick coal seam in the Fushun coal field,a new formation mechanism for the continental extra thick coal seam,i. e.,lacustrine allochthonous-microallochthonous mixed peat accumulation mechanism,which is related to the river and strom events,are demonstrated In this new mechanism,the storm current or subaquatic gravity current induced by storm not only transported the organic and inorganic clasts formed in lakeshore swamp and delta into the central lake,but also redeposited the peat clasts in deeper water environment,separating effectively the inorganic clasts from the peat clasts.