The invention discloses a measuring and calculating method for water conserving and storing capacity of a drainage basin based on soil freeze-thawing. The method comprises the following steps: firstly, processing basic data; secondly, calculating the soil freeze-thawing hydrothermal state in the drainage basin, so as to obtain the proportion of ice content in the soil; then, quantitatively expressing the temporal distribution of the water conserving and storing capacity at various grid points in the drainage basin, and calculating the grid-type soil water conserving and storing capacity index; finally, calculating the water conserving and storing capacity at grid points in a sub-basin of each stage, drawing discretized cumulative distribution curves of the water conserving and storing capacity in all the sub-basins so as to obtain a dynamic measuring and calculating model of the water conserving and storing capacity of soil in the drainage basin of a freeze-thawed area, and measuring and calculating the water conserving and storing capacity of the drainage basin during the soil freeze-thawing. According to the invention, a numerical model is built for a point-scale melted snow-frozen soil hydro-thermal coupling system, and establishes relationship with the water conserving and storing capacity of soil in drainage basin grids, so that the water conserving and storing capacity index of the drainage basin at spatial scale is set dynamically to coincide with the actual situation, and errors caused by the homogenization of a cold region drainage basin are reduced.