This paper analyzes timespace variability of watersalt in unsaturated soil of an experimental area during soil freezing and thawing (initially freezing period, maximum freezing depth period and thawing period) with their semivar iogram. Conditional simulation of geostatistics is used to reproduce well the fl uctuation of soil watersalt with fewer sampling points. The paper analyzes and evaluates the Ordinary Kriging method and Conditional Simulation by comparing th em. The laws of values of seed of stochastic series and length of stochastic series affecting computing accuracy and efficiency of Conditional simulation are discus sed in detail and the stable ranges of their values are obtained.