The 21-year-old front-man has made a big impact at Boro since joining from Darlington in 2011.
He has scored five times in 25 games, and is a firm favourite with the fans for his all-action displays and commitment.
He has been involved for Boro this season, but Tony Mowbray is keen for him to see more first-team action and now he is set for a month-long move.
A number of League One clubs had shown an interest but it is Shrewsbury who are set to claim Main's signature.
Main will join current Boro youngster Adam Reach at the New Meadow, after he joined the Shrews earlier this month.