Yes, but GaussDB(DWS) clients and drivers are recommended. Unlike open-source PostgreSQL clients and drivers, GaussDB(DWS) clients and drivers have two key advantages:

Security hardening: PostgreSQL drivers only support MD5 authentication, but GaussDB(DWS) drivers support SHA256 and MD5.
Data type enhancement: GaussDB(DWS) drivers support new data types smalldatetime and tinyint.

GaussDB(DWS) supports open-source PostgreSQL clients and JDBC and ODBC drivers.

The compatible client and driver versions are:

PostgreSQL psql 9.2.4 or later
PostgreSQL JDBC Driver 9.3-1103 or later
PSQL ODBC 09.01.0200 or later

For details about how to use JDBC/ODBC to connect to GaussDB(DWS), see Tutorial: Development Using JDBC or ODBC.

Does GaussDB(DWS) Support Third-Party Clients and JDBC and ODBC Drivers?