Ronchin (French pronunciation:) is a commune in the Nord department, Hauts-de-France, France. It is part of the European Metropolis of Lille.
Population
| Year | Pop. | ±% p.a. |
|---|---|---|
| 1968 | 14,030 | — |
| 1975 | 15,319 | +1.26% |
| 1982 | 17,367 | +1.81% |
| 1990 | 17,937 | +0.40% |
| 1999 | 17,999 | +0.04% |
| 2007 | 18,614 | +0.42% |
| 2012 | 18,398 | −0.23% |
| 2017 | 19,220 | +0.88% |
| 2023 | 19,787 | +0.49% |
| Source: INSEE | ||
Heraldry

The arms of Ronchin are blazoned:
Or, on an escarbuncle sable a ruby gules. (Abscon, Beuvry-la-Forêt, Erre, Fenain, Marchiennes, Ronchin, Tilloy-lez-Marchiennes and Wandignies-Hamage use the same arms.)