Abstract: The effect of boundary layer height (BLH) of Tibetan Plateau on atmospheric circulation is studied by the communi ty climate model (CCM3), and the observation result s of second scientific experiment on the Plateau is also combined.Evidence shows that BLH contributes to the st rong development of vert ical motion at the southeast part of the Plateau and the Yangtze River valley, along w ith air flow enforcement of convergence (divergence) at the lower (upper) level.Deepen BLH is also beneficial to remarkable increase (decrease) in cloud and precipi tation in the Yangtze River valley and the Yellow River area.