Abstract: The end cover fixing part of a special sealing box was avulsed at work, which caused the attachment to fall off. By analyzing the tearing mechanism of the fixed part, it was concluded that the reason for the avulsion of the fixed part was the insufficient strength of the fixed part and the unreasonable distribution of the connecting holes. The number of layers of the fixing part material was studied, the compression rate of the glass fiber was improved, the strength of the fixing part material was enhanced, the distribution of the connecting hole of the fixing part was simulated and analyzed, the position of the connecting hole was redistributed, the distribution of the stress between the holes was improved, and the damage degree of the glass fiber caused by the processing connecting hole was reduced. By optimizing the shape of the fixing part, the bonding strength between the fixing part and the end cover was further improved. After experimental verification, the improvement measures of the end cover fixing parts improved the avulsion strength of the fixing parts.