Research results: The relative construction technique was applied in construction of pile foundation and cap of pile trestle of Kaixinling Bridge 1# on Qinghai-Tibet Railway and solved the difficult problem of drilling on the pile foundation of bridge in permafrost area.
Research conclusions: In construction of pile foundation of bridge in permafrost area, it was better to use big power rotary drilling machine for rapid cavity making, but the following things should be noted: the process of concrete grouting had not to be interrupted, full preparation would be done, the connection of procedures would be short after excavation (drilling) would be quick, the time of soil exposure would be short after excavation(drilling) and the measure against sunshine would be taken if necessary, the speed of grouting concrete would be as quick as possible and the measure for maintaining concrete would be reliable.