A garbage truck driver has been charged with dangerous driving, after a grandmother was crushed to death while pushing her grandson in a pram on Sydney's northern beaches.

The woman, believed to be in her 50s, was on Pittwater Road in Dee Why when she was struck before midday on Thursday, police said.

The young boy, aged about two, was located in a pram nearby and was not injured.

The 27-year-old man driving the truck was charged with dangerous driving occasioning death and negligent driving occasioning death.

He was granted conditional bail and is due to appear in Manly Local Court on March 7.