By default, your Dropbox folder is stored in your Users folder at C:\Users\<username> (or your Home folder in OS X and Linux). If you want to move it somewhere else, though, the process is quite simple.
Why would you want to move your Dropbox folder in the first place? It really depends on your setup. Perhaps you have a smaller drive for your operating system (like an SSD) and use a larger, secondary drive for storage. Or maybe you prefer to keep it directly inside your Documents folder, or somewhere else entirely. The why is really up to you. There are a few caveats you should keep in mind when deciding on a location for your Dropbox folder, though:
You shouldn’t store it on a removable drive. Dropbox requires a constant connection to the folder to ensure that sync works. Even an external drive that’s always connected to your computer could become disconnected or powered off. So it’s best to either keep it on an internal, permanently connected hard drive.
Dropbox won’t work with network shares. During normal syncing activity, Dropbox monitors for drive update events to know that a file has changed and it should start syncing. Physically connected drives send these events to the OS. Network drives do not.
Don’t move your Dropbox folder manually–move it with the Dropbox app. If you move your Dropbox folder out of the location where Dropbox expects to find it, Dropbox will recreate the folder and resync the whole thing.
When you’re ready to move your Dropbox folder, click the Dropbox icon in your system tray (or menu bar, in the case of OS X), click the Settings icon, and then choose Preferences.
In the Dropbox Preferences window, switch to the Account tab. Next to the current folder location, click Move.
Browse for the new location you want. A folder named Dropbox will be created inside whatever folder you choose, so don’t create a new folder named “Dropbox”–just pick the folder you want your “Dropbox” folder to reside in. Click OK.
Click OK to tell Dropbox that you are sure about the move.
Click OK to have Dropbox move your files to the new location, and continue using Dropbox as you always have. That’s all there is to it.