Based on the theory of evanescent wave，a muliti-core all fiber device is investigated with kinds of fibers by fused biconical taper technics，which can be used for laser beam combination. The insertion loss of the fiber device is smaller，and the fiber coreparallelism is better. The devices of 19 and 37 fibers have been successfully manufactured. The insertion loss of the device is less than 1 dB. The new fiber device provides fiber amplification network an integrated fiber bundlearray，thatimprovesthespaceutilizationandisconvenientfortheapplicationofthelargescalefiberenvironment.