When the loan is RMB 200,000 and RMB 8,000 per month, the calculation method of interest on 36 installments is as follows:

1. First calculate the total repayment amount of 36 installments and multiply it by 8,000 yuan per month to get 288,000 yuan.

Secondly, the total amount minus the loan amount is 288,000 yuan minus 200,000 yuan to get 88,000 yuan.

3. The final interest is 88,000 yuan.