What were factors for the collapse of Ming Dynasty?

Well, there are several reasons.
1. The expropreation of farmland had made more and more refugees.
2. The taxes were quite heavy which made the farmers join in the team of refugees.
3. The rules of the army were very relaxed and the soldiers hurt the common people casually.
4. They had failed some important battles.
5. The emperor had used the wrong people which ruined his empire.
6. The emperor was very Narrow minded and he was afraid that someone may rob his power.