Detective Acting Inspector Craig Mansfield said there was an altercation between a 24-year-old man and the teen girl at the Big4 Hervey Bay Holiday Park, about 300km north of Brisbane, around 9pm on Saturday.
The girl allegedly stabbed the man once in the back.
He was taken to hospital but died from his injuries.
The girl was taken into custody by Queensland Police and later charged with murder.
Another 14-year-old girl witnessed the incident and is assisting police with their investigation.
Police allege the victim and the accused met a matter of hours before the fatal incident.
"There's more questions than answers at this point in time but what we do know so far is that the there is a very limited relationship between this male deceased and our 14-year-old female," Det Insp Mansfield said.
"It is not random that they have met, there is some connection between those witnesses or the accused."
A weapon has not yet been located but items that could have been used in the alleged murder were being tested, Det Insp Mansfield said.
He said the 24-year-old man had links to Hervey Bay but was transient and living out of a car before the murder.
"We're trying to establish his patterns of movement leading up to the incident," Det Insp Mansfield said.
Police are going through mobile phones and CCTV footage to establish the full picture of why the incident unfolded.
The teen will face Hervey Bay Children's Court on Monday.
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