The degradable aliphatic/aromatic copolymer fiber is prepared with random copolymer of aliphatic butanediol succinate and aromatic butanediol terephthalate and through melt spinning. The copolymer has the structure as shown. The aliphatic/aromatic copolymer fiber may be stretched stably and has excellent processing performance. During the preparation process of the fiber, the copolymer solution in characteristic viscosity of 0.6-1.4 is melt spun at the speed of 500-5000 m/min to obtain the copolymer fiber with strength greater than 2.5 cN/dtex. The degradable aliphatic/aromatic copolymer fiber may be used in weaving fabric for clothing and non-weaving field.