To defeat Fire Man, as the battle begins, run towards him then jump over his shots. His shots move along the ground & leave bonfires where you got hit or jumped over the shots. A good strategy is to keep moving close to him so he doesn't shoot; when he runs back, just jump over him then move along close to him behind. To attack, stop following him then shoot once, when you hit him, he will counterattack. If you let him go farther from you, he will shoot a barrage of Fire Storms, so stay as close to him as possible. Do not rapid fire him or he'll counterattack with a barrage as well. With this strategy, you will surely be unscathed.
Here's another quick strategy, as the battle begins, ready to press the Jump & Shoot buttons simultaneously when Fire Man shoots. Jump over the first shot, either you get hit or luckily dodged the shot, continuosly do the Jump-Shoot maneuver on a stationary position until you defeat him.
Fire Man is weak against Ice Slasher which you will get if you defeated Ice Man beforehand. Do the above strategies for an easy win.
In Dr. Wily Stage 4, you will encounter him again for a rematch. Use the strategies above to defeat him using Ice Slasher.
Fire Man only appeared in The Beginning in the animated series of Mega man with no lines.