The invention discloses a ray energy detection method for a ray detector, which comprises the following steps: a) detecting rays by a crystal probe and converting the detected rays into signal pulse; b) acquiring the standard waveform of the signal pulse of the ray detector based on a plurality of non-piled signals preset by the signal pulse in the step a), and using the standard waveform as the reference waveform of the ray detector; c) based on the standard waveform, obtaining an energy correction table of the ray detector; and d) according to the energy correction table, performing energy interpretation on the non-piled signals of the ray detector so as to obtain ray energy corresponding to the non-piled signals, and correcting pile signals so as to obtain ray energy respectively corresponding to the pile signals. According to the method of the invention, the conventional exponential hypothesis model is replaced by an actual measurement and statistic method, so the method not only improves the detection precision of the ray detector, but also does not need changing hardware of the prior detector, and is simple and effective.