可以修改，但是只能修改一次。
以OPPOR9S手机使用手机微信V7.0.3版本为例，修改方法如下：
一、手机打开微信进入后，点击页面右下角的“我”，然后选择“设置”选项。
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二、进入设置以后，选择“帐号与安全”选项。
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三、然后找到“微信号”一栏并点击进入。
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四、进入以后输入要设立的微信号，然后保存即可。
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参加资料来源：/kf.qq.com/faq/161224Z7fU3M161224nQBfmQ.html"target="_blank"title="微信官网-微信号设置/修改">微信官网-微信号设置/修改