The preliminary results came as tallies from last week referendum began to be posted outside polling stations in southern Sudan.
The preliminary returns must be verified by electoral officials in Juba before official results are announced, probably in a few weeks.
The Chairman of the Southern Sudan Referendum Commission, Mohamed Ibrahim Khalil, praised the vote.
"I have watched a number of elections in this country and I think this has been the most peaceful, the most orderly and the quietest and I think it is really a great achievement," said Khalil.
He said more than 80 percent of the nearly four million registered voters had cast ballots, far surpassing the 60 percent turnout needed for the results to be valid.
A 50 percent majority must vote for separation to fulfill the second requirement for independence.
Several thousand observers from Sudan and abroad monitored the vote. European Union observer Martin Ehrenhauser expressed satisfaction with the process so far.
"This procedure has happened in a very peaceful, secure and a very well organized manner. And now we are starting the last part of the voting," he said. "And what I can say so far is that, also, this part of the procedure is very well organized."
The African Union issued a preliminary report saying it found the vote to be free and credible, and a true reflection of the will of the Southern Sudanese people.
Sudan’s President Omar al-Bashir visited the region before the referendum and said his government would accept the results.
If confirmed, the new state is expected to emerge in six months, when the Comprehensive Political Agreement between north and south is due to expire. The accord, signed six years ago, ended two decades of civil war and paved the way for the referendum.
But observers say many issues remain to be resolved. These include border demarcation, the division of oil revenues and external debt payments and the future of the Abyei region where clashes last week killed several dozen people.