I don't think China counts as a "Major Industrial Nation" yet ~ though clearly it should but Chinese domestic economy is still very much biased toward farming, at least in the eyes of the Yanks who seem to decide these things.
Try this for a definition of Major Industrial Nations ~ and I'm not saying it is right but it does seem to demonstrate the thinking behind such titles.
The G8 Group is an unofficial forum of the heads of the leading industrialized democracies (Russia, the U.S., Britain, France, Japan, Germany, Canada and Italy), where the European Commission is also represented and fully participates. This forum was designed to harmonize attitudes to acute international problems. The member states account for 49% of global exports, 51% of industrial output, and 49% of assets in the International Monetary Fund.
You will note that China does not get a mention.