According to a newspaper report, the body is believed to be that of a transient.
The body was found by a man and his two sons inside the cave, east of Glenwood Springs, on Saturday afternoon.
The deputy coroner of Garfield County told the Glenwood Springs Independent that the hands of the corpse were starting to mummify, indicating that death had occurred weeks before the trio made the grisly discovery.
Thomas Walton was conducting an autopsy to determine and the cause and time of death for the unidentified man.
For years, cavers trying to visit Cave of the Clouds have been confronted by a wild-eyed transient who sometimes threw rocks at them as they climbed the walls of Glenwood Canyon to access the cave.
The man told cavers that he considered the cave his home and he stayed there year round.
A spokeswoman for the Garfield County Sheriff's Office said the man found dead had been living in the cave.
The man and his sons planned to revisit the cave to erect a cross in his memory.
Source: The Denver Channel