 The problem of forest effects on regional precipitation is very complex which has been existing in the fields of forestry ecology， forestry meteorology and forestry hydrology for over one hundred years．Any wrong analytical result will lead to much confusion in ideology and misplay in practice． Therefore， the researches and disputes to the problem are significant in both theory and practice． Viewing from paralleling observations， statistical analysis and simulative modeling used in some typical literatures，the primary and qualitative results were obtained．The results show that there exist big differences between different research methods due to subjectivities in almost every method． The further search should not only be focused on the physical mechanisms of atmospheric boundary but also physiological and ecological characteristics of forests and grass and soil water balance as well．Especially，with the variations in vegetation coverage，water consumption of vegetation，dynamics of soil water，and possible changes of regional water resources should be paid more attention to，which is much more important in regional ecological restoration and construction．