The formation of the Mongol Union by Genghis Khan led them to confront regional and extra-regional opponents. With the beginning of the first disputes between the Mongols and the Khwarezmshahian, the Mongol army headed towards Iran. The current research, using the descriptive-analytical method and using first-hand sources, seeks to answer the question, what methods did the Mongols use to conquer different regions of Iran? The findings of the research show that the Mongols used a combination of erosive, surprising and bloodthirsty war methods in the face of the resistance that was carried out in different regions. Due to the fact that the Mongols did not face a unified army, they used different methods and tactics to conquer different areas. They use methods such as creating fear and panic by sending envoys, capturing villages and surrounding areas before conquering the main urban centers, dividing military forces and fighting simultaneously on several fronts to prevent the unification of enemy forces, long-term siege and surrendering the enemy using catapults. Using incendiary materials to break the siege and evacuate hiding places in cities, using tricks to surprise or trick the enemy, such as pretending to retreat, spreading rumors, offering peace, camouflage, delaying the enemy to arrive for reinforcements and reinforcements, and using captives They used war in the battle with the enemy.