In order to improve the transmission performance of optical fibers, an air holes and grooves six core optical fiber structure was designed. In multi-core optical fibers, each core is surrounded by a layer of low refractive index grooves, with a cladding layer between the core and the grooves, and an air hole auxiliary structure surrounding the fiber. Based on the coupled-mode theory of optical fibers, an in-depth analysis was conducted on three transmission characteristics: crosstalk, mode field area, and bending loss. The research findings indicate that the fiber with the air holes and grooves structure exhibits the best performance in terms of inter-core crosstalk, achieving a minimum crosstalk value of approximately -55 dB. On the other hand, the single-trench-assisted structure effectively increases the mode field area of the fiber, reaching a maximum value of about 390 μm². However, the variation in bending loss across different structures does not show a clear pattern, with its logarithmic values concentrated in the range of 4~9 dB/m.