Environment evolution is revealed since about 100 years in Lake Hongjiannao, Shaanxi Province according to sporopollen analysis, after comparing with lithological character, historical records and instrumental data.The results show that before 1927 the regional climate was very dry in Lake Hongjiannao with typical hungriness vegetation, and the lake did not come into being.Between 1927 and 1938, the dryness degree of climate gradually eased up, lake hasin depression began to collect water and lake formed.The vegetation type turned to be hungriness and brushwood-shrubbery vegetation between 1938 and 1960 as the regional climate relatively got better and local environment began to become wet.Under the relative better climate condition Lake Hongjian-nao received more amount of water and became a deeper lake than 1927-1938; the vegetation type was grassland and brushwood-shrub vegetation.Around 1960 the local environment had tlie greatest change, as indicated by sporopollen diagram, which showed the superimposed influence of the human activities and precipitation increase in the region.Between 1960 and 2000, climate evidently improved than that of former several stages.The continuous wet environment led to the steady higb-stage lake level after short-time widening in about 1960;the corresponding vegetation was typical, with more flourish grassland and brushwood-brush.In recent years, the lake area began to turn relative dry again.The vegetation type was meadow and grassland vegetation dominated by Chenopodiaceae.