The invention belongs to the field of welding and particularly relates to moderate-temperature Zr-based brazing filler metal special for Ti2AlNb-based alloy identical or different material brazing anda preparation method and a brazing process of the brazing filler metal. According to weight percentage, the brazing filler metal comprises 5%-30% of Fe, 1%-15% of Nb or 1%-20% of Cu, <=5% of oligoelements including one or two or more of Al, B, Co, Cr, Mn, Mg, Ni, Ag, and Zn, <=2% of microelements including one or two or more of Ti, Hf, V, Ta, Mo, W, Au, Si, Sn, Pd and Ga, and the balance of Zr elements and unavoidable impurity elements. The preparation method of the brazing filler metal comprises the steps that firstly, raw materials are weighed; secondly, mother alloy of the brazing filler metal is smelted; and thirdly, the smelted mother alloy is subjected to quenching melt-spinning, and then the brazing filler metal is obtained. The brazing filler metal is used for brazing according tothe brazing process of 960 DEG C to 1,030 DEG C and 0-120min. Compared with existing brazing filler metal, the prepared brazing filler metal has an appropriate melting point, excellent wettability and high-temperature mechanical properties, and brazing filler metal preparation and the brazing process are simple.