The Ryonggang Line is a non-electrified standard-gauge secondary line of the Korean State Railway located entirely within Namp'o Special City, South P'yŏngan Province, North Korea, running from Ryonggang on the P'yŏngnam Line to Mayŏng.

[1] The Ryonggang Line was originally opened as the Yonggang Line by the Chosen Government Railway (Sentetsu) prior to 1937.

[2] Most freight on the line is outbound from a mine at Mayŏng and a granite quarry on the Husan Line.

A local train, 734, operates on the entirety of this line from Mayŏng to Ryonggang, continuing on to Kangsŏ on the P'yŏngnam Line, with a scheduled travel time of two hours fifteen minutes according to the 2002 timetable; the return trip is train number 733, taking two hours to make the trip.

[1] A yellow background in the "Distance" box indicates that section of the line is not electrified.