The invention relates to a multi-fiber core single-mode optical fiber and a manufacturing method thereof. The multi-fiber core single-mode optical fiber comprises claddings and a plurality of fiber cores. The multi-fiber core single-mode optical fiber is characterized in that the fiber cores include a pumping fiber core and a plurality of signal fiber cores, wherein the pumping fiber core is arranged in the center of the optical fiber, the signal fiber cores are distributed on one to three circumferences around the center at equal intervals, so as to form one to three layers of signal fiber cores, sunken claddings tightly cover each signal fiber core, and common claddings are arranged outside the sunken claddings. The multi-fiber core single-mode optical fiber has the characteristics of low signal crosstalk among all of the signal fiber cores, easiness in online light amplification, simplicity and convenience in manufacturing and low manufacturing cost and is suitable for large-scale production. A distributed Raman amplification technique of the multi-fiber core single-mode optical fiber is used in an ultrahigh-speed communication system, so that effective light amplification can be realized, and the harm of a non-linear effect to the performance of a high-speed optical transmission system is further reduced.