call the tablesSet () function every time you click the tab. The elementUI table defaults to fixed layout, and the column width is set by table width and column width
tablesSet () {

    var tables=document.querySelectorAll('table');
    for(var i=0;i<tables.length;iPP){
      tables[i].style.width='100%'
    };
    var elHeaders=document.querySelectorAll('.el-table__header');
    for(var j=0;j<elHeaders.length;jPP){
      elHeaders[j].style.tableLayout='inherit'
    }

}