The suspended particle material (SPM) samples of surface seawater were collected on the board at 45 stations along the shipping line of Xuelong Ship. The natural abundances of 15N in SPM were measured and the distributions of δ15N along the shipping line were studied. The δ15N values varied from 0.57‰ to 9.87‰ with the mean of 4.12‰. The δ15N distribution showed trans-sea area characteristics and it increased or decreased sharply on sailing from one into the other sea area. The lowest δ15N values with the average of 1.65‰ were observed in Southern Indian Ocean.