It's understood 29-year-old Craig Church died after falling down several flights of stairs in the apartment block where he lived in eastern China.
He had been working as an English language teacher at a primary school in Rui'an for the past two years.
His sister, Carrie Church, told BBC Radio Foyle he was a "fun-loving man".
"He was a friend to everyone," she said.
Ms Church said the family was working closely with the Kevin Bell Repatriation Trust to have her brother's body returned home.
"It's all very raw for us," she said. "He was amazing and loved his job. People adored him in China."
"Craig was your friend if you were young or old," his sister added.
"We are just devastated. He was the best brother, son and friend."

The supermarket's stock fell by more than 4% to close at 197.8p.
Over the weekend, press reports suggested the deal faced a lengthy investigation from competition regulators.
Shares in Booker also fell, with the FTSE 250 company down 3.6%.
Overall, the FTSE 100 ended down by 66 points at 7,118.48. Most major stock markets around the world fell after President Donald Trump's decision to impose a travel ban on seven Muslim-majority countries.
Among the gainers in the UK, Vodafone rose after the mobile phone company said that its Indian unit was in merger talks.
A combination of the two companies would create India's biggest telecoms firm. Shares rose 1.3%.
On the FTSE 250, shares in WS Atkins jumped 6% following a report in the Times that the engineering company had been approached by US company CH2M over a possible merger.
Flybe shares dipped 1.1% after the airline said it had seen a "slow start" to trading since the start of the new year, blaming "uncertain consumer confidence and poor weather".
That was despite the carrier reporting "solid" trading for the final three months of 2016, with revenues boosted by extra capacity. Flybe said passenger revenues rose 13.5% in the quarter, compared with 5.7% in the previous six months.
On the currency markets, the pound fell 0.5% against the dollar to $1.2484, but rose 0.4% against the euro to 1.1682 euros.

The 22-year-old has scored 11 times in 18 games in the seventh tier this season and will join the Premier League champions' under-23 side for the rest of the season.
Rangers said: "We are proud to have played a part in a young man's journey to a top club."
Gordon had eight years at Stoke before dropping into non-league football.
Former Leicester player Stan Collymore began his career with Stafford, while Foxes and England striker Jamie Vardy started out at Stocksbridge Park Steels, also in the seventh tier.
Find all the latest football transfers on our dedicated page.
The sister of a Portstewart man who died in a tragic accident in China on Tuesday, has said the family is "shocked and heartbroken".
[NEXT_CONCEPT]
Shares in Tesco led the declines on the FTSE 100, giving up some of Friday's gains when the stock surged in the wake of news of its planned tie-up with food wholesaler Booker.
[NEXT_CONCEPT]
Leicester City have signed forward Josh Gordon from Northern Premier League Premier Division side Stafford Rangers.