The waveform of tidal geoelectrical field is an approximate sine wave. The TGF-A waveform appears in all-day and the TGF-B only appears in the prenoon-postnoon. The harmonic periods of the waves of first 5 orders are 23∼24, 12, 7.9, 6 and 4.8 h, respectively. On different sites, the amplitude spectrum of the tidal geoelectrical field could be different. The vertical and horizontal tidal forces produced by the moon change periodically, of which amplitude spectra are also different. To the different directions of crack planes, the tidal forces generate varied effects. This could be the reason for the different amplitude spectra of the tidal geoelectrical field. On the same site, the obvious difference of the directional waveform characteristics in wave amplitude and stability could be caused by the preferential orientation of cracks. The wave amplitude of the tidal geoelectrical field is much larger and stable along the preferential orientation, and on the contrary, the wave amplitude is smaller and could be unstable in the direction perpendicular to the cracks. The cracks of mesh shape could cause similar waveform characteristics in all directions. The characteristics and amplitude spectra can be used to estimate water seeping direction and crack plane direction. The analysis result of dominant crack orientation on several sites is roughly consistent with the regional or local stress field.

Site‐selective phenomenon exists in the normal waveforms of the geoelectrical fields of Qinghai‐Tibetan Plateau and its adjacent areas: rock structure of the sites, cracks and fissure water, tectonic activity and other factors affect the normal waveforms of the geoelectrical field; a large lake will contribute to the occurrence of TGF‐A waveforms nearby, TGF‐B waveforms will mostly occur in the areas where there are thick Quaternary sediments, and high water content and good water permeability of rocks, while the geoelectrical fields with no diurnal variations are prone to appear in the bedrock mountains where there are intense tectonic activities. Before moderate or strong earthquakes in the region, short‐term and impending anomaly of the geoelectrical field has a cluster phenomenon, in which there is a temporal synchronization or a few days' difference, while spatially it can be distributed near several faults in the region, manifested as a discrete phenomenon. This phenomenon of temporal clustering and spatial scattering is the short‐term and impending precursor characteristics of the geoelectrical field in the region. The Σ – Δ summation method is introduced to analyze the usual stability of spontaneous field through the observational data of the geoelectrical field, which indicate that before a moderate or strong earthquake, background value jumps of part of geoelectrical fields are a transformation phenomenon of spontaneous field; the concept and calculation method of TA, which is the sum of the first 10 order tidal harmonic amplitudes divided by the sum of the first 100 order harmonic amplitudes, are established to show quantitatively that the tidal effect of waveforms of TGF‐A, TGF‐B and non‐diurnal variation is successively reduced; the first order difference method of ΔE is adopted to analyze the higher frequency electromagnetic components in the minute order geoelectrical field monitoring data, usually the high‐frequency jumps show a certain degree of randomness and limitedness. By using three different methods of analysis, the features of spontaneous field, the telluric field and high‐frequency electromagnetic components are analyzed from the composition of the geoelectrical field, which provides a theoretical and methodological basis for the physical analysis of the geoelectrical field.