Abstract: The investigation depth at where the steady-state Rayleigh wave exploration could be arrived is a topic with which the numerous users are more and more comcerned.Starting fron the basic principal of Rayleigh wave exploration and practical experiences for many years,in this paper the various factors which have influence on the exploration depth,including the mean velocity vR of rock beds,the used lowest frequency fmin,source energy,various geologic factors,coupled factors and so on are analyzed one by one,and the example data of exploration depth under various conditions are listed.It is pointed out that utilizing compre-hensively the rational parameters and further increasing the recognition capacity for small anomalies,the current exploration depth of Rayleigh wave method could be increased.