The Sichuan-Tibet Railway is located in the high-cold and alpine valley area of the plateau， and the railway tunnel survey is very difficult. The author has carried out the research and development of 1000m-level horizontal wireline coring drilling technology and equipment， and conducted application demonstration in the DZ-Kazila Mountain No.1-Directional Experiment-01 hole of the Kazila Mountain No. 1 Tunnel on the Sichuan-Tibet Railway. The 1212m horizontal directional test hole was successfully completed， and 3 faults and 19 joint fractured zones in steep dip strata were identified. The error in azimuth was less than 1°， the hole inclination was 0.76°/100m， the mechanical drilling rate was 3.09m/h， and the rig-month efficiency was 350.29m， which created two depth records of 588m and 974m each for PQ and HQ sizes in China. The difficulties on transportation in inaccessible areas and on identification of the structure of mixed steeply inclined rock formations were overcome， and breakthrough was made with horizontal “line” surveys in place of the past vertical “point” surveys. With the horizontal directional coring hole， rock lithology， high dip formation structure， and hydrology at the tunnel section can be directly identified. It can provide a reference for solving the difficult exploration of long and deep buried tunnels on plateau railway； and has the role of demonstration and promotion.