Using this query you can easy to get all primary keys of from all tables of current database.
SELECT i.name AS IndexName,
OBJECT_NAME(ic.OBJECT_ID) AS TableName,
COL_NAME(ic.OBJECT_ID,ic.column_id) AS ColumnName
FROM sys.indexes AS i INNER JOIN
sys.index_columns AS ic ON i.OBJECT_ID = ic.OBJECT_ID
AND i.index_id = ic.index_id
WHERE i.is_primary_key = 1
Output will be like this.