Hi @博雄 胡
It seems like a by design issue. SQL Server 2012 introduced a new designer for maintenance plans so if you try and edit an earlier version of a maintenance plan with SSMS 2012 it will be saved in the new format, then the lesser versions of SSMS will not be able to open it.
Reference [MSDN article], point 5.5:
5.5 New Maintenance Plan Layout Not Compatible with Earlier SQL Server Tools Issue:
When SQL Server 2012 management tools are used to modify an existing maintenance plan created in a previous version of SQL Server management tools (SQL Server 2008 R2, SQL Server 2008, or SQL Server 2005), the maintenance plan is saved in a new format. Earlier versions of SQL Server management tools do not support this new format.Workaround: None
Referring from this thread: SQL Server 2012 Maintenance Plan can't modify.
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