Re: in the different schema ，the sequence name is same， and a table's column definition use this sequence,so，how can I identify sequence's schema name by system view/table:

This is better asked on the pgsql-general mailing list, but the short answer is that you have to look at your search_path as well. Since you just created schema_1, and public is in your search_path, a plain seq_xx_yy is the one from the public schema. To see the fully-qualified name, run:

SET search_path = pg_catalog;

before issuing your select from information_schema.columns