China's exports grew 1.0 percent year-on-year in July, well below market expectations of an 8.6 percent rise, while imports grew 4.7 percent, against a 7.2 percent forecast.

Benchmark 10-year T-note yields fell 5.5 basis points to 1.6420 percent, while T-note futures rose 21/64 to 133-25/32.

"The weaker Chinese data hit equities and further supports what a lot of people have been talking about, namely diminishing growth expectations out of China and that's having a 'risk-off' effect," said Craig Collins, a trader at Bank of Montreal.

T-note yields hit a 2-1/2 month high on Thursday after recent US jobs data beat expectations and as investors made room for a large amount of new government paper.

The Treasury Department sold $16 billion of 30-year bonds on Thursday. It sold $24 billion in 10-year notes on Wednesday and $32 billion of three-year notes on Tuesday.

"Now that supply is out of the way, the market is ready to go higher again," Collins said.

Uncertainty over when the European Central Bank will resume bond purchases and how effective this will be in lowering Spanish and Italian yields and easing the euro zone's debt crisis also underpinned safe-haven Treasuries.