Abstract: The basis principle of Karhunen-Loeve (K-L) transform is sketched out in this paper. On the basis of this, the theoretical foundation of inhibition the noise and increase signalnoise rate of seismic record is expounded. And based on the theoretical models, the test research and analysis has been done.
The results show that the effect of inhibition the noise with K-L transform has relation to the closely relevant event on the seismic record and the number of characteristic value. When K-L transform was done for the record of the closely relevant event is better, and the number of characteristic value is chosen
at the inflection point of the curve, the effect of transform isachieved. Otherwise, the number of the number of characteristic value can not be defined exactly. Thereby the effect of inhibition the noise will be decrease.

Key words: K- L transform, signal-noise rate, event, feature value