Using the hydrographic data obtained from two sectional observations crossing the Luzon strait in the summer of 1994 and in the winter of 1998, the volume transport through this strait is calculated. It is found that in winter the volume transport (4.45 × 106 m3/s) is far larger than that in the summer (2.0 × 106 m3/s), respectively being about equal to 15.0% and 6.9% of the Kuroshio.And the paths of water in and out of the section of the strait vary distinctly with the season. In summer, the water flows in and out of the South China Sea (SCS) three times: that is, the inlet passages almost appear on the southern sides of the three deep troughs,the outlet passages are all located on the northern sides of the troughs,and the in-out volume transports through the channel are not lower than 4.0× 106 m3/s. The highest velocity (＞80 cm/s) and the largest entering water capacity (6.6× 106 m3/s) all occur in the Balintang Channel. Except for the north outlet passage in the section, all the higher velocities over 10 cm/s are mainly distributed on the layer above 500 m. In winter,the water flows in and out of the strait two times :the southern sides of the second and third deep troughs are the main passages of the Kuroshio water running into the SCS,while the whole section of the first deep trough and the bottom section of thesecond deep trough are the outlet passages. The higher velocities over 10 cm/s are almost distributed on the layer above 300m. Numericalcalculation shows that the northern side of the third trough may be the outlet passage.