Combined with the theory of sequence stratigraphy and hydrocarbon accumulation, the characteristics of sequence stratigraphy and hydrocarbon accumulation mode of CI oil group in Tazhong 4 oilfield are discussed which is based on the sequence characteristics and sedimentary system and hydrocarbon accumulation conditions,etc. Using the datum of seismic, well logging and coring, CI oil group in Tazhong 4 oilfield can be divided into 2 third-order sequences, 5 subsequences units, 9 parasequences, and both tidal and Delta depositional systems have been identificated by research of faces in the trellis of sequence stratigraphy. On the basis of the sequence and sedimentary characteristics, hydrocarbon accumulation elements of petroleum geology are analyzed, and hydrocarbon accumulation along the fault-transporting allochthonous model has been established. For hydrocarbon sources rocks are hardly found in CI oil group,oil and gas comes mainly from the underlying Ordovician and Cambrian source rocks,reservoirs are mainly distributed in transgressive system tracts of SQ1 and SQ2. Oil and gas along the big break migrated up to CI oil group and accumulation. There types of reservoirs of lithologic hydrocarbon, faults-lithologic hydrocarbon and micro-anticline are developed.