The invention discloses a monitoring data compression method applicable to an operation and maintenance automation system. The method includes the following steps that 1, data preprocessing is conducted, wherein smoothing is conducted on original data to reduce interference with an SDT algorithm from noisy data; 2, preliminary data compression is conducted, wherein a control algorithm is adopted to compress data preliminarily; 3, further data compression is conducted, wherein the SDT algorithm is adopted for further compression; 4, SDT compression precision parameter matching is conducted, wherein after each time of data compression, compression precision parameters are matched with the characteristics of data fluctuation changes according to the data fluctuation changes, and compression precision parameters generated after matching are obtained; 5, adaptive adjustment of the SDT compression precision parameters is conducted, wherein the step 2, the step 3 and the step 4 are repeated according to the compression precision parameters generated after matching, and then the compression precision parameters are adaptively adjusted; 6, the step 2, the step 3 and the step 5 are repeated until the compression precision parameters are completely matched with the characteristics of the data fluctuation changes, the optimal compression precision parameters are obtained, and then the step 2 and the step 3 are repeated to complete data compression.