Abstract: in order to study the pore structure features of sapropelit,based on the cryogenic nitrogen adsorption and mercury intrusion test,the pore fractal theory was applied to discuss the pore structure and fractal features of sapropelite. The results showed that sapropelite would havethreedifferent pore size distributions. Type I would have high contents of the micropore and mesopore and the 4 nm cracks were well developed.Type Ⅱ would have micropore and small pores well developed and the max pore diameter was 2,4 and 30 nn. Type would have the pores generally poor developed.Sapropelite pores would have fractal features,the datafrom the mercury intrusion test showed that the comprehensive factal dimension of the pore volume was 3.17~ 3.90,and the data from the cryogenic nitrogen test showed that the fractal dimension of the pore specific surface area was 2.59~2.93.The comprehensive fractal dimension of the pore volume and the general area of the pores would be in a positive related relationship. With the comprehensive fractal dimension increased ,the micropore content would be increased and the mesopore andmacropore contents would be decreased.The fractal dimension of the pore specfic surface area and the porosity would be in a weak posive eated relationship and would have a negative related relationship to the ash content.T'he metamorphism would have a homogenization role to thepore structure of sapropelite.