Abstract: A stainless steel sheet generated cracks during the course of braze welding,and means such as macroscopic observation,micro-zone morphology and compositions analysis were used to analyze the reasons for cracks.The results indicate that the melting copper particles penetrated into the stainless steel grain boundaries during welding and formed brittle film in the grain boundaries,so copper brittleness was the main reason for cracking of the stainless steel sheet.Finally,some corresponding improvement measures and recommendations were put forward based on the failure reasons.