In this paper, by using a simple climate model (SCM), a numerical simulation study has been conducted on the scientific and methodological aspects of Brazilian Proposal. First the initial check of simple climate model has been done, then we do some sensitivity studies on timeframes (attribution start and end dates,and evaluation date), and three attribution methods (marginal attribution method, proportional attribution method, and time-sliced attribution method), at last we get the main conclusions as follows: The simple climate model can represent the results of more complex climate model (e.g., HadCM3), and it is thus used to study the scientific and methodological aspects of the Brazilian Proposal. Because of the limited knowledge of science and data, although attributing a part of temperature increase to different GHG (greenhouse gas)emission source, there is considerable temperature increase unattributed to regional emissions. Therefore it is uncertain to make Brazilian Proposal as the method for the responsibility share of future GHG decrease emission. The choices of different timeframes (attribution start and end dates, and evaluation date)and future emission SRES (Special Report on Emission Scenarios) make great influence on the regional contributions to global climate changes, but different attribution methods have only a little influence.