简单介绍了零件表面荧光背景不良的4种类型。重点针对表面黄绿色背景显示进行工艺分析与对比试验，验证了导致此背景不良的主要原因是:吹砂机在处理机加零件时，砂粒被切削液污染；在较高压力下，被污染的砂粒造成其他零件的二次污染；荧光渗透检测前，二次污染未被去除，黑光灯下呈现出大面积黄绿色不良背景。最后，提出了工艺改进措施，措施实施后提高了产品的缺陷检出率，保证了企业的正常生产。

This paper expounds four types of poor background parts and lays key point on the process analysis and process improvement through contrast test. It was verified that the main causes of poor background fluorescence were due to the contaminated sand while the blowing sand machine was in processing the parts. Under high pressure, the contaminated sand caused secondary pollution of other products. Before FPI process, the secondary pollution of products was not cleaned off, so large yellow-green areas were presented. In this paper the technological improvement measures are put forward to improve the defect inspection rate and ensure the normal production of enterprises.