based on the video tutorial from LearnFlash.com

In this tutorial, you will create particle fire effect that will simply be a looping MovieClip that symbolizes a flame. You will then attach it to stage many times via ActionScript 2.0, then a randomize script will randomize its position, alpha, frame number of the timeline, and size of the flame. Overall, it's a great tutorial if your looking for a realistic fire effect within Adobe Flash. Let's get started!

Step 1: Create fire particle within a MovieClip named "flame"

Step 2: Create a new MovieClip out of the particle and rename it "particle"
Note: So now you have a parent MovieClip named "flame" and inside of it is a MovieClip named "particle". If preferred, the MovieClip Used can be replaced for a different one.

Step 3: Animate the MovieClip "particle" upwards and fade to an alpha of "0"

Step 4: Set up the MovieClip "flame" to be called using external linkage via ActionScript

Step 5: Add the following script into the Actions by selecting the first frame and pressing F9

this.createEmptyMovieClip("holder_mc", this.getNextHighestDepth());//The amount of particles that you want createdvar particleCount:Number = 150;
 
for(i:Number = 0; i < particleCount; i++){
 
var flameParticles:MovieClip = holder_mc.attachMovie("flame","flame" + i, holder_mc.getNextHighestDepth());
 
//Sets the particle's  y position
 
flameParticles._y = 350;
 
//Sets the particle's  x position
 
flameParticles._x = Math.random() * 60 + (Stage.width/2 - 30);
 
//Each flame particle creted has random scale dimensions
 
flameParticles._xscale = t._yscale = Math.random() * 80 + 20;
 
//Plays at a different frame during every loop
 
flameParticles.gotoAndPlay(Math.ceil(Math.random() * 16));
 
//Possible rotation property
 
//flameParticles._rotation = Math.random() * 10;
 
}

Video: Fire Particle Effect

Original source of video