The hearing had been scheduled for Friday. South African media said the reason for the postponement was so Steenkamp's family could provide submissions.
"It has been postponed until Oct. 21. I have not been given the official reason for this," family spokeswoman Anneliese Burgess said.
Pistorius, a Paralympic gold medallist, was due to have been released on parole in August after serving 10 months but Justice Minister Michael Masutha blocked his release, saying the parole hearing had been held prematurely.
The Parole Review Board upheld Masutha's decision this week.
However, now that the athlete has served a sixth of his sentence, the parole board can legally consider whether or not he should be released to serve the rest of his sentence under house arrest.
Pistorius was found guilty in September 2014 of culpable homicide, the equivalent of manslaughter, after he fired four 9 mm shots through a locked toilet door at his Pretoria home, killing Steenkamp almost instantly.
At a globally televised trial he argued that he had mistaken Steenkamp for a burglar.
Prosecutors are appealing the culpable homicide verdict, arguing it should be murder because Pistorius must have known that the person behind the door could be killed. That appeal is due to be heard on Nov. 3.
(Reporting by Zandi Shabalala and Ed Stoddard; Editing by Ed Cropley)
