Sun who joined from Manchester City just a year ago really excelled when he begun the first 14 or so games for the Blades, but after a crazy red card against Coventry City in a midweek tie, he failed to cement his place back into the backline after Kyle Naughton well and truly took over.
Kevin Blackwell understands Sun's problems and had no qualms in him returning back to China. He said: "We have allowed Sun to move back to China. Although his mum was over here he missed his family greatly and wanted his kids to be schooled over there.
"The situation made him slightly uncomfortable so I didn't want to keep him like that. He is a great professional and a good lad who taught the young lads quite a lot and we wish him all the best."