A nine-year-old girl was reported missing from the Mount Wilson property at approximately 8.20am today.
Officers said the child has been missing since yesterday.
Hundreds of officers, along with State Emergency Service (SES) and Rural Fire Service (RFS) crews, search through the dense bush of Mount Wilson.
Staffs search tents and boxes for any sign of a child.
“A command post has been set up at Mt Wilson RFS station with RFS and SES volunteers assisting police from Blue Mountains Region Command, Police Rescue, Dog Unit and PolAir,” NSW Police said in a statement.