Based on the Tibet Autonomous Regions statistic yearbooks and the data from the two household surveys in 2002 and 2004, this paper has comprehensively analyzed the pattern of changes on the farmers and herdsmens income sources in the Tibet Autonomous Region since 1990 with the main findings as follows: ① The change of income from the labor payment is the fastest; ② There is no regular pattern of income variation for the household economic activities, the farmers and herdsmens household income generation projects are impacted by the elements like prices and returns, and there is a lack of appropriate direction; ③ The income structure of labor payment shows that the income from the farmers and herdsmen working outside grows fastest; ④ The income from the farmers and herdsmens labor payment correlate positively to their net income per capita; ⑤ From the perspective of the variation by region, labor payment income has changed fastest in the counties of Rutok, Nyerong and Khangmar compared the data from the household survey in 2002 with that of 2004.