The invention provides a continuous metallic glass fiber and a preparing method thereof. The alloy component of the metallic glass fiber is one of palladium base, platinum base, gold base, calcium base, magnesium base, copper base, aluminum base, titanium base, iron base, cobalt base, nickel base, zirconium base, hafnium base, yttrium base and lanthanide series rare earth base, the diameter of the cross section of the fiber is 2 to 50 mu m, the length thereof is more than 100m, and the volume content of amorphous phase thereof is not less than 90 percent. Super-cooled metallic glass alloy melt is drawn into the metallic glass fiber of a certain diameter at a tremendous speed through a porous wire-drawing bushing. The metallic glass fiber has excellent comprehensive mechanical property. The continuous metallic glass fiber can be made into primary products such as rope, cloth, net, felt, short-cut yarn, and the like, in the application mode which is similar to that of oxide glass fiber; or on the basis, the fiber can be used as fiber reinforcing material to be combined with resin, ceramics, metal, cement, plaster, asphalt, and the like, thus producing various composite materials with rich and changeful performances.