The Exeter–Plymouth line, also called the South Devon Main Line, is a central part of the trunk railway line between London Paddington and Penzance in the southern United Kingdom. It is a major branch of the Great Western Main Line and runs from Exeter St Davids to Plymouth, from where it continues as the Cornish Main Line. It was one of the principal routes of the Great Western Railway which in 1948 became part of the Western Region of British Railways and is presently operated by Network Rail.

Exeter St Davids railway station is the principal railway station serving the city of Exeter in Devon, England. It is 193 miles 72 chains from the zero point at London Paddington, on the line through Bristol which continues to Plymouth and Penzance. It is also served by an alternative route to London Waterloo, via Salisbury, and branch lines to Exmouth, Barnstaple and Okehampton. It is currently managed by Great Western Railway and is served by trains operated by Great Western Railway, South Western Railway and CrossCountry. It is the busiest station in Devon, and the third busiest station in South West England.