The invention relates to a method for non-destructive testing of preservative-treated bamboos or wood. The method includes the steps of obtaining a sample by treatment with a preservative; scanning ametal element standard sample by using synchrotron radiation X-rays, and correcting synchrotron radiation energy by using a K absorption edge; obtaining a series of X-ray projection images by performing continuous exposure imaging on the sample with each interval of energy T, and causing third radiant energy and fourth radiant energy with the difference of energy T to correspond to a first X-ray projection drawing and a second X-ray projection drawing; and selecting the first X-ray projection drawing and the second X-ray projection drawing to perform subtraction to obtain distribution of metalelements. The method has accuracy in detection and is convenient to operate, suitable for non-destructive testing of preservative-treated bamboos and also suitable for non-destructive testing of preservative-treated wood.