Abstract: Cracking failure happened to epoxy-filled dry-type transformers during using procedure.In order tofind out the cracking reason,magnetic induction intensity measurement,wire resistance measurement and X-rayscanning analysis were done to the failure transformers.The results indicate that the cracking of the transformerwas caused by the irrational design on the fixing plate which wasnt arc processed.Stress concentration formed atthe sharp corner during the pouring seal and made cracks form at the sharp corner during the high & lowtemperature test and finally caused the transformer cracking and black material outflowing.