A mother and father who sexually, physically and psychologically abused their daughter for more than a decade conditioned her to expect such treatment and to believe it was normal, a court has heard.

Judge Sarah Huggett said she had to put aside her "natural feelings as a human to the profoundly disturbing way the victim was treated" in sentencing the parents for the abuse they inflicted on their daughter from the age of 5 to 19.

Those who sat in on the 12-week trial have described it as the worst case of child abuse they have heard.

In her sentencing remarks in Sydney Downing Centre District Court on Thursday, Judge Huggett said it was "rare" to see a case of such severe mistreatment of a child.

As the court heard the distressing details of abuse the daughter was subject to, she was in a separate room watching the sentencing via audio-visual link.