没有找到直接的接口，不过，可以自己模拟一下：
在cellwidget的外层添加一层透明窗体，在这层透明窗体上添加布局，将cellWidget放入布局中，对布局进行对齐设置。
示例代码：
QWidget *translateWidget = new QWidget(m_ptablewnd);
translateWidget->setObjectName("translateWidget");
translateWidget->setStyleSheet("background-color:rgba(0,0,0,0)");
QHBoxLayout *hbl = new QHBoxLayout();
hbl->setSpacing(0);
hbl->setContentsMargins(0,0,0,0);
hbl->setMargin(2);
translateWidget->setLayout(hbl);
QPushButton *button = new QPushButton (translateWidget);
hbl->addWidget(button,1,Qt::AlignCenter);
button->setToolTip("Hello");
button->setIcon(QIcon(a.png));
button->setFixedSize(64,64);
hbl->addWidget(button);
QTableWidget *tableWidget = QTableWidget();
tableWidget->setRowCount(1);
tableWidget->setColumnCount(1);
tableWidget->setCellWidget(0,0,translateWidget);
