Abstract: Railway development histories of some developed countries and China and the future trend of railway traffic in the world are introduced. Railway transportation's superiority and its important role played in economy construct are described. The existing problem of railway transportation and key mechanics problems of train/railway at high-speed to be urgently solved are discussed. They mainly include: (1) pantograph-catenary/ train/track(bridge) system coupling dynamics; (2) vehicle structure strength and reliability problems; (3) wheel/rail performances(derailment, adhesion, rolling contact fatigue, corrugation and noise); (4) pantograph-catenary dynamics of high-speed train and wear and tear under the condition of high-speed current collection; (5) key mechanics problems of track structure and destructive problems of track engineering under atrocious environment. These problems have an important effect on traveling safety and running quality. Main directions to solve these problems in the future are presented.