We can't get a work permit for him until China rise up the FIFA rankings
Apparently there's another way he could get back here without China climbing the rankings.
this article explains it.
http://c.newsnow.co.uk/A/896056813?-11200:789:0West Bromwich Albion will be able to recall Zhang Yuning from his loan at Werder Bremen after just one season - but only if he enjoys an outstanding campaign in Germany.
The Chinese striker was immediately loaned to Bremen after signing for the Baggies earlier this summer for an undisclosed fee believed to be €9 million (£7.9 million).
The loan is for two years, yet Albion could be in a position to recall Zhang after less than 12 months.
Zhang does not currently qualify for a UK work permit given the restrictions that exist concerning players whose nations lie outside the top 50 in Fifa's world rankings.
China, whom Zhang has represented on nine occasions, are 77th in the rankings and unlikely to break into the top 50 in the immediate future.
But the 20-year-old could still earn enough performance points to acquire a UK work permit next summer and facilitate an early recall to the Hawthorns.
To do so, he will need to exceed all expectations for appearances and goals in the Bundesliga, considered one of the most competitive leagues in world football.
"The situation is very, very good for us, that we have Chinese owners and we can get an exciting young Chinese player brought into the club," Baggies boss Tony Pulis said.
"Now he’s got two years in Germany to prove it to himself, to prove it to us when we watch him.
"Hopefully he will reach that standard, then we can bring him back to England in a year if he does exceptionally well this year.
"Then China will have a centre forward playing in the Premier League which will be brilliant."