解决方法:禁用headerview的ResizeToContent:
Qt 4.*
pTable ->horizontalHeader() ->setResizeMode( QHeaderView::Fixed );
pTable ->verticalHeader() ->setResizeMode( QHeaderView::Fixed );
Qt 5
pTable ->horizontalHeader() ->setSectionResizeMode( QHeaderView::Fixed );
pTable ->verticalHeader() ->setSectionResizeMode( QHeaderView::Fixed );