Abstract: In order to observe the change of extracted main chemical component content and aroma mechanism of Aquilaria sinensis. This test treat A.sinensis with different resin contents as objects to compare and analysis the microstructure and segregation structure. The results show that resin mainly distribute in xylem ray and included phloem, the companion cells play an important role in resin formation, sieve tube and other cells play helping role in this progress. This progress mechanism is essentially the same as parenchymal cell behavior before they die in progress of heartwood formation. There is a negative correlation between ash content and extractives. It indicates that the aroma of A.sinensis has important relation with moisture in xylem.