接公安局通知，留学生的签证办理将做以下变动：

1. 对于持有居留许可的学生，请至少提前30天到深圳市公安局出入境管理处提交延期申请，否则不给与办理；
2. 对于持非居留许可类签证的学生，请至少提前7天到深圳市公安局出入境管理处提交签证申请，否则不给与办理；
3. 新签证签发需15个工作日；
4. 新居留许可的有效期至少为180天。

According to the Shenzhen Public Security Bureau, policies of Visa Application have the following important changes:

1. Student who holds residence permit (student visa) must submit your visa application to Shenzhen Public Security Bureau at least 30 days before your visa expires; otherwise, application will not be accepted.
2. Student who holds L-visa, F-visa or X-visa must submit your visa application to Shenzhen Public Security Bureau at least 7 days before your visa expires; otherwise, application will not be accepted.
3. The processing time is 15 working days after you submit your application.
4. The validity of your new residence permit is 180 days or more.