If you ship something from China to Korea, usually there are four ship ways, China Post/DHL/China EMS/Fedex, China post is more affordable while DHL and Fedex is more faster and expensive.
How long does it take to ship a package from China to Korea?
DHL express service takes 2.5 days (based on 209 DHL shipments)
China Post service takes 17.6 days (based on 3601 India post shipments)
China EMS service takes 8.7 days(based on 1576 China EMS shipments)
Fedex takes 6 days(based on 15 shipments)
This data is base on TrackingMore’s tracking data, you can check How long will India Post take to get a package from China to Korea yourself.
About the tracking data
We can see the fastest way is DHL express service, 98.6% of packages are delivered in 7 days. While the China post service is slower and cheaper, 47.2% of packages are delivered between 16 to 30 days. You can go to TrackingMore’s site to know more about this Estimated delivery time caculator. Btw, if you want to get the lastest update of your package, you can also check Trackingmore's China post tracking page and Korea post tracking page.