Abstract: This paper contrasts runoff change and main influence factors of Bahe River and Jinqianhe River on north and south slopes of the Qinling Mountains，aims to reveal the difference in hydrology and climatology change in the north and south Qinling Mountains，to provide a quantitative analysis data base for the climate change research of the Qinling Mountains region. Based on runoff、precipitation data of Maduwang and Nankuanping Stations from 1960 to 2011，the mathematical statistical methods such as concentration period，M-K mutation，runoff coefficient were used and compared runoff variation of Bahe River basin and Jinqianhe River basin and revealled the difference in environmental change of the south and north Qinling Mountains. The conclusions are as follows：（1） The trend of variation in annual mean runoff depthes of Bahe and Jinqianhe River basins basically was similar during the last 52 years，the runoff change reflected a wave rise from 1960s to 1990s，after 1990s it showed an obvious fluctuation decline trend. The annual runoff depth variation of Jinqianhe River was greater than that of Bahe River. （2） The annual runoff variation tendency of Jinqianhe and Bahe Rivers was consistent in the last 50 years，the runoff is mainly concentrated in summer and autumn seasons，the runoff and precipitation have a lag effect in the Qinling Mountains river basins；it takes about 20 d from the basin precipitation beginning for rainwater storage stopping，overflowing，river tunnel collecting，and then converging to rives of the north and south Qinling Mountains. （3） The time mutation points of the runoff in the Qinling Mountains were characterized by consistency，they all occurred in 1990 or so，the mutation is not caused by local human activities，but due to the larger scale climate change which leads to a change in the local natural environment. （4） The runoff depth decreased significantly after mutation than before mutation in Bahe River and Jinqianhe River basins from 1960 to 2011，the precipitation showed a trend of decrease as a whole in Bahe River and Jinqianhe River basins，indicating that the precipitation is one of factors affecting the runoff depth.  Their runoff coefficients had a downward trend，meaning that part of rainfall converting to runoff becomes less and less in the north and south Qinling Mountains，the part of rainoff that is intercepted by plants or filled into depresses，infiltration and evaporation increased，this is due to the increased temperatures increasing vegetation activity，thus making the runoff a decline trend. （5） During recent 50 years，the Jinqianhe River was affected by human activity are much smaller than the Bahe River.  The runoff coefficients and double mass curve method were used to analyze quantitatively runoff change effect factors，the conclusion shows that the combination of climate change and human activities influences the runoff variation. The mutations of runoff in the late 1990s was mainly caused by climate change. In fact，some obvious mutation phenomenon is caused by the heavy climate change，the impact of human activities on the natural environment is slow in time，and the process of governance also requires a lot of time and money，so the development and management for natural resource should be taken simultaneously.

Key words: the north and south Qinling Mountains, climate change, runoff change, concentrated period