Buying a second-hand house in Longquan, Chengdu with a loan of 200,000 yuan and a guarantee fee of 6,000 yuan. Is it reasonable?

This is definitely unreasonable. The so-called guarantee fee is actually just another means for intermediaries to make money. The money really paid to the bank is at most 1000 yuan. You can go to the guarantee company for a loan. Some big intermediary companies have set up loan departments to deposit some money directly, but you still have to figure out your loan policy first.