I m going from new Delhi to Montreal, one hour layover at terminal 3 of Beijing Capital Airport.

If you take connecting flight, then you don't need to worry about transfer time. The flights of Air China both arrive and departure at T3.

Generally speaking, after you arriving International Arrival Level at 3F of T3-E, you need to proceed with transfer procedures, and pass through the Transit Inspection in special passage, go to 2F of T3-E and accept Security Inspection, then wait to board.