Abstract: Oil and gas leakage system develops in Yinggehai Basin，northwestern South China Sea，which is composed of the mixed type of gas chimney，sea bed dot/pit like “micro leakage”，and oil/gas seepage “marcro leakage”，the oil/gas mixed system oil/gas seepage and gas chimney on eastern Yinggehai slope is more remarkable，and the gas chimney at mud diapir belt in the central depression of the central basin and dot/pit like “micro seepage” system on the sea bed are quite common.In the area，hydrocarbon source is abundant and up to now，it is still in the process of dynamic reservoir formation of generation，accumulation，gathering and dispersion，there is good condition of hydrocarbon generation，migration，accumulation and reservoir formation.It is recognized that key breakthrough for hydrocarbon exploration is to enhance the comprehensive analysis and research on oil/gas seepage system and migration，accumulation and reservoir formation.The proposal is suggested that the theory of dynamic balancing reservoir formation of oil/gas migration and accumulation should be used to predict and evaluate favorable hydrocarbonrich area and optimize the explorative tar.gets with good trap and preservation.

Key words: oil and gas leakage system, oil and gas surface seepage, gas chimney, micro leakage/macro leakage, trap storage conditions, oil and gas dynamic balancing reservoir