Assuming you know the other module's ModuleID, you can use the module controller to load an instance of the module's settings for that module.  Something like:

Dim oController as DotNetNuke.Entities.modules.ModuleController
Dim oSettings as HashTable

oSettings = oController.GetModuleSettings(OtherModuleID)

if you need to find the other ModuleID, you can look based on the Friendly name.. and/or the module's title on the tab.

Paul.

sorry; my last post was very unordered!

thanks paul i wrote my codes like this:
DotNetNuke.Entities.Modules.ModuleController oController = new ModuleController();
Hashtable Settings = oController.GetModuleSettings(381);
Map.Key =Settings["DNNInfo_GoogleMap_GoogleAPIKey"].ToString();

but oSettings returns nothing and at the third line so it returns "object refrence not set to an instance of object"