Police allege FaCS disability support worker Lennard Michael Downes, 35, was secretly recorded verbally and physically abusing the boy over a two-day period at a government-run care centre in the Illawarra in November last year.

It is alleged Mr Downes repeatedly called the boy a "f---ing c---" while trying to feed him and threatened to hit him if he didn't eat.

The recording also picked up several sounds, which police will allege are Downes slapping and hitting the boy.

Downes was arrested on December 22 and charged with assault occasioning actual bodily harm. He was released on strict bail.

In court on Wednesday, defence lawyer Alyce Fisher formally entered a plea of not guilty on behalf of her client and sought a hearing date.

Up to 10 people are expected to give evidence in the case, which could run for up to two days.

The first day has been set down for November 13.