In the latter half of the eighteenth century, a new political system emerged in Tibet: the Dalai Lama became the head of the government and his four bka'blon, government ministers, organized the ministry with the support of the Qing Dynasty. Because this system is followed even today and the bka'blon have played an important role in Tibetan politics all this while, we can consider the latter half of the eighteenth century as an important period for Tibetan politics. I studied how the bka'blon were chosen and examined the relationship between Tibet and the Qing Dynasty. The three main results were as follows. First, the Qing Emperor merely ratified the bka'blon chosen by the Dalai Lama government. Second, although it has been said that the four bka'blon shared an equal status in the ministry, there did exist a political ranking system among them. Third, Bstan 'dzin dpal 'byor was chosen as a bka'blon even though he had no title. In conclusion, although it appears that the Qing Dynasty intervened in Tibetan politics, it actually permitted Tibet to rule by their own methods.