With wave spectrum analytical techniques of spatial geochemical data, one can obtain abundant information of the geochemical field, understand characteristics of geochemical fields of study areas from various aspects, extract essential oil and gas related knowledge from all kinds of data, pick up more accurate anomalous oil and gas information and objectively predict oil and gas perspective areas. Case histories show that low frequency filtering reveals the main features of geochemical field, intermediate frequency filtering is consistent with oil and gas fields, and high frequency filtering reflects shallow effects and noises which are difficult to be interpreted. By combining low and intermediate frequency results with results from different frequency fields, one can pick up anomalous oil and gas information more precisely.