from PyQt4.QtGui import QTableWidget, QTableWidgetItem, QHeaderView

# 创建表格
table = QTableWidget(5, 3)  # 5行3列
table.setHorizontalHeaderLabels(["列1", "较长的列标题", "列3"])

# 设置最小列宽为标题宽度
header = table.horizontalHeader()
header.setResizeMode(QHeaderView.ResizeToContents)  # 先根据内容调整
header.setMinimumSectionSize(header.sectionSize(0))  # 设置最小宽度为当前宽度
header.setResizeMode(QHeaderView.Interactive)  # 恢复可交互调整

for col in range(table.columnCount()):
    header.resizeSection(col, header.sectionSize(col))
    header.setMinimumSectionSize(header.sectionSize(col))