Owing to the special structure between fiber and crystal, single-crystal fiber has the merits of both fiber and crystal medium. For its advantages of high gain, simple thermal management, and small nonlinear effect, single-crystal fiber is widely used in ultrashort pulse amplification. The experimental research progress in single-crystal fiber amplifiers is reviewed. Firstly, two kinds of single-crystal fiber preparation methods including micro-pulling down technique and laser heated pedestal growth technique are introduced. Then along the principal clue of various means to improve the amplification performance of single-crystal fiber amplifiers, we summarize the research progress in Nd∶YAG and Yb∶YAG doped single-crystal fiber amplifiers and some new amplifiers with special structures in ultrashort pulse amplification. Finally, the applications and future development trends of single-crystal fiber amplifiers are prospected.