The calibration errors are analyzed in the aspects of radar parameter measurement,A/D transformation, video integration processing, precision and stability of measuring instruments, etc, through demonstrating the principles and method of CTL713C digital weather radar echo intensity calibration, and the possible error corresponding to each case is given, respectively. The possible calibration errors in echo intensity resulted from the measuring environment and manual operations are discussed, and the method for examining the accuracy of calibration results of radar echo intensity is described. The key issues in radar echo intensity calibration are summarized.