Abstract: A statistical analysis about the distribution of soil water content was made based on the 3022 measured data sampled from the area around 800 km² at Tongzhou district of Beijing. The results showed that the soil water content followed the logarithmic normal distribution, so an estimated method was also put forward to predict the reasonable number of sampling in a similar region. The study results will be applied to indicate scientifically how and how many monitoring stations of soil water content are set up. The experimental and theoretical analysis from another region at Changping district of Beijing also verified above results.