Abstract: The conditional simulation is one part of the interdisciplinary subject-geostatics.The theory can keep spatial correlation of variables as a strict mathematical simulation to reproduce dispersion variance and fluctuation process. It has been drawn great attention in geology,water resources,soil science and environment science etc. After a brief introduction to the theory and methods of conditional simulation,the article reviews the main achievements of its application to water resources system and the development of new methods and techniques at home and abroad in the nineties of the 20th century,and looks into the future of the subject and its technique development.