Abstract: Si Keshu River is characterized by winter flood, occurence of which is because of the sutburst of ice lakes along the river. This paper is meant to discuss some physical geographic problems related to winter flood. The research results show that the genesis of vinter floods has close relation with the given climate, valley and river beds. The valley of Si Keshu River is a oblique valley with alternative appearence of broad and narrow alleys. The longitudinal section of the valley is low with many menders. There are many soulders on river beds. These factors are favourable for the formation and development of ce dikes and lakes.