To evaluate the efficiency of biological pump and carbon sequestration content on Arctic shelf, estimations of POC export fluxes derived from 234Th/238U disequilibrium and organic carbon burial rate from 210Pbex chronology in sediment core were made during the Chinese 3rd National Arctic Research Expedition (CHINARE-3), Jul 12~Sep 22, 2008. Great deficits of 234Th to 238U were observed widely over Chukchi shelf, with an average 234Th/238U)AR. Of 0.64?.28, resulting from intense particle scavenging. The average POC export fluxes in entire study area, shelf and slope area were 24.9?3.3, 29.5?3.0 and 2.1?.5 mmol C m"2 d"1, respectively, I.e. 21％ of the primary production on average were exported to the benthos. Organic carbon burial rate of 517 mmol C m"2 a"1 were estimated, accounting for 6 ％ of the average primary production. The efficient biological pump led to 11.6?.0 T g C exported to benthos and 3.4 T g C buried permanently in the sediment per year, accounting for 0.3 ％ of total POC export amount and 2.1 ％ of total organic carbon burial amount of global ocean.