Transport · Cross-Border · Mongolia
Beijing to Ulaanbaatar — Trans-Mongolian Railway
The Trans-Mongolian Railway runs from Beijing to Ulaanbaatar in approximately 30 hours, crossing the Chinese-Mongolian border at Erlian/Zamyn-Üüd where the bogies are changed to accommodate different track gauges.
Route & practicalities
The Trans-Mongolian Railway is one of the great overland rail journeys in Asia. Operated on Train K3/K4 (Chinese Railways) or Train 3/4 (Mongolian Railways), the service departs Beijing Railway Station weekly. Journey time to Ulaanbaatar is approximately 30 hours.
The route passes through Inner Mongolia and arrives at the Chinese border town of Erlian (二连浩特), where the train undergoes a bogie exchange — China uses the standard gauge (1,435 mm) while Mongolia uses the wider Russian broad gauge (1,520 mm). The exchange takes approximately three hours, during which passengers remain on the train and watch the procedure through windows. Border officials conduct passport and customs checks during this period.
Tickets for the Chinese segment are purchased via 12306.cn. The international K3/K4 tickets are available through China International Travel Service (CITS), specialist rail agents, or directly at Beijing Railway Station's international ticket window. Booking well in advance (3–4 weeks) is advisable for berth availability.
Cabin classes: soft sleeper (four-berth compartment) is the standard for this journey. Hard sleeper (six-berth) is available at lower cost. The soft sleeper dining car serves Chinese food on the Chinese segment; the wagon changes to a Mongolian dining car at Erlian.
Customs and duty: standard Chinese customs declaration applies at departure. Mongolian customs checks at Zamyn-Üüd. The 1.5-litre per person alcohol duty-free allowance applies. Currency declaration is required for amounts above USD 15,000 in Mongolia.
What to expect at the border
The bogie exchange at Erlian takes 2–3 hours overnight. Border officials board the train, check passports, and conduct a brief cabin search. Customs declaration forms are distributed. Mongolian officials board at Zamyn-Üüd for the Mongolian entry check. The crossing is generally smooth and experienced travellers find it an interesting part of the journey.