In this work,a seven-core fiber is designed with the beam propagation method and the finite element method,the inf luence of the key parameters on the transmission properties of the seven-core fiber is inves tigated,and the seven-core optical fiber is fabricated with the optimized structural parameter s.An experiment setup is built to characterize the multi-core fiber (MCF),with which the transm ission loss,the bending loss and the crosstalk of the seven-core optical fiber are measured.The results show a transmission loss of 0.36dB/km,a bending loss of 0.0537dB and a crosstalk of －18.5dB.The seven-core fiber proposed here has the advantages of simple preparation and good performance,and could play an important role in the development of the space-division-multipl exing (SDM) technology.