declaration

our company plan to purchase some aircraft tools, using the FOB terms. Do we must declare at the custom by the forwarder or myself?[size=3][/size]

If you are the one to purchase, you are the importer.  You need to arrange the vessel and inform your supplier.  The customs declaration process and fees are for your suppliers' account.  Not only that, the shipping charges at their local port are also for their account.  When the goods arrive in China, you have to arrange the customs declaration by yourself on your own account.