Abstract: On the base of the introduction of joint time-frequency analysis principle,the behaviors of time-frequency distribution on transient response signals of several geoelectric models are studied.It is demonstrated that under the general trend of the time-frequency distribution strength weakened with the depth,the strength is changed obviously by the effect of resistivity,the strength is larger when the resistivity is lower and vice versa. Thus,the relationship between the joint time-frequency distribution of transient fields and geoelectric structure is established and the transient field data could be interpreted better.