Is china a semi-periphery country?

I think the consensus is that over the last 20 years or so China has gone from the periphery to semi-peripheral status. There are various ways to categorise countries, but the most important seems to be to do with how much profit (sometimes called value-added) is made on the kinds of economic processes that happen within them. So, to make aluminium, you first mine bauxite, which doesn't make much profit. This kind of activity tends to happen most in peripheral countries, so they stay relatively poor because they don't see much return on their economic activities. Processing the bauxite into aluminium, though, brings a bigger profit (because only so many countries have the technology, capital, skilled labour etc. to be able to to this, and so they have a relative monopoly) and these more highly profitable activities tend to happen in the core, meaning that core countries tend to get allocated a bigger share of the global surplus accruing from all world economic activity. Obviously, some lower profit activities happen in the core, and some higher profit processes in the periphery, but we are talking in terms of general trends here.

Semi-peripheral economies don't usually do the kind of 'intermediate' jobs along the production chain, as you might think, but instead tend to have a diverse mixture of core-like industries and peripheral-like ones. China's economy is very much like this, so we call it semi-peripheral country. The difference between China and most semi-peripheral countries is that its particular history means it has a semi-peripheral economic structure, but it's social structure looks more like a peripheral country still (more peasant farmers and a smaller- though growing- urban working class). This means its wages are lower than most semi-peripheral countries and so it has a big advantage in production over most of the rest of the semi-periphery because it can produce goods much more cheaply.