On the master, run:
mysql> SHOW GLOBAL VARIABLES LIKE 'binlog_format';
This variable will be either ROW, STATEMENT, or MIXED.
Note that the global default doesn't preclude individual sessions from changing their binlog format, and DDL statements are always logged in STATEMENT format regardless of what binlog_format is set to.
See http://dev.mysql.com/doc/refman/5.6/en/server-options.html#option_mysqld_binlog-format