我找到了解决办法：

return Container(
      decoration: const BoxDecoration(
        color: HGVColors.grey,
      ),
      child: Row(
        mainAxisAlignment: MainAxisAlignment.spaceEvenly,
        children: menuItems
            .asMap()
            .entries
            .map(
              (x) => InkWell(
                onTap: () => setTitle(x.key),
                child: Column(
                  mainAxisAlignment: MainAxisAlignment.center,
                  children: [
                    SvgPicture.asset(
                      "assets/images/${x.value.icon}.svg",
                      height: 25,
                      color: getColor(x.key == currentIndex),
                    ),
                    child: Text(
                      x.value.label,
                      style: TextStyle(
                        color: getColor(x.key == currentIndex),
                      ),                      
                    ),
                  ],
                ),
              ),
            )
            .toList(),
      ),
    );

密钥是mainAxisAlignment: MainAxisAlignment.spaceEvenly。