Technical parameter, characteristics and overall layout of DMUs for Sri Lanka railway high-mountain line were introduced.Field tests were put forward including traction accelerated velocity, highest operation velocity, braking distance, performance of long grade and continuous small curve passing, grade manual parking ability, single locomotive traction performance, resistance braking performance and self-loading performance, which proved the DMUs adapted the high-mountain line operation conditions of continuous long grade, small radius curve, high altitude, high wetness, and heavy rain.