When I create new feature in editing session, I need to determine the new created feature is in which layer because after that have further more action on the layer. I wonder can this be done in vb.net arcobjects?
I am using vs2012 and arcmap 10.2.
Yes. You need to respond to the IEditEvents.OnCreateFeature which returns an object of type IFeature which has a property Class which will give you the feature class it belongs to.
After you have the feature class belonging to the new feature you can iterate through your editable layers (using IEditLayers.IsEdtiable) and see if the (ILayer as IFeatureLayer).FeatureClass matches - this will tell you what layer it is.