Some theories and measurement techniques of the electrochemical methods, ion selective electrode and Eh, are introduced simply in this paper.
On the basis of data obtained form the field of Lüjing earthquake (M=3.4) 1980, it is indicated that there are obvious precursory anomalies for the fluorine, nitrate and Eh before the earthquake. On the other hand, we accentuate that the electrochemical method have some excellent features, for example, less instruments required, simplicity of operation, convenient to observe at field, easily to make up measurment continually and automatically, etc. It is an effective and practicable method to set up comprehensively hydrochemical observation.
We are sure that these methods would play an important part in the research of prediction earthquake.