Slash stated in his autobiography that he and Duff McKagan wrote the main riff to "Rocket Queen" when they first got together in the short-lived band Road Crew with Steven Adler, prior to Slash and Adler joining Hollywood Rose.

According to frontman W. Axl Rose:

I wrote this song for this girl who was gonna have a band and she was gonna call it Rocket Queen. She kinda kept me alive for a while. The last part of the song is my message to this person, or anybody else who can get something out of it. It's like there's hope and a friendship note at the end of the song. For that song there was also something I tried to work out with various people—a recorded sex act. It was somewhat spontaneous but premeditated; something I wanted to put on the record.

A credit in the booklet for Appetite for Destruction reads "Barbi (Rocket Queen) Von Greif", implying that she was "this girl" Rose mentions in the quote. Slash states that, while Von Grief was only eighteen at the time, she had a notorious reputation and was "a queen of the underground scene back then. She'd eventually become a madam, but Axl was infatuated with her at the time." She was also mentioned in the acknowledgments section of L.A. Guns' self-titled debut album.

In an October 1991 interview in Guitar Player magazine, John Frusciante of the Red Hot Chili Peppers said Axl Rose told the Chili Peppers that Guns N' Roses had the Chili Peppers in mind when they did Rocket Queen.

A woman named Adriana Smith had been with drummer Steven Adler for around a year. Smith later claimed in a TV interview that, after Adler insisted that she was not his girlfriend, she went to the mixing sessions at Mediasound Studios in NYC. Rose and Slash were there. Rose propositioned Smith that they have sex in a vocal booth so that the sounds that Smith made could be recorded and put over the bridge of the song. Smith replied that she would do it, "For the band, and a bottle of Jack Daniel's".

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Wikipedia