Litter amount and its dynamic change of four typical plant community under the fenced condition in desert steppe were studied. The result showed that the litter amount of four typical plant community under the fenced condition were in the sequence of Agropyron mongolicum Keng(116.8g/m²)> Glyeyrrhiza uralensis(101.6g/m²)> Leymussecalinus(97.8g/m²)> Artemisia desertorum(88.1g/m²), and there were 5.0, 4.8, 5.3 and 1.6 times than that under grazing condition, respectively. Change pattern of four typical plant community litter showed an increasing trend during growth season (from June to October), and there were negative relationship among litter amount and rainfall, temperature. The amount of different organs were in the sequence of leaf(59.25%)>branch(30.75%) >miscellany(10.00%), and standing dead litter account for 60% of litter amount. Comparative analysis between simulated and observed values of litter amount and litter dynamic fit by Birk model, the litter amount increased with increase years in desert steppe, and litter amount comes to a steady state after fenced for 7-10 years. The exchange between input and output reached balance.