A curved multi groove assisted 6-core fiber structure has been designed, where each core in the multi core fiber is surrounded by three identical low refractive index grooves, and there is a layer of cladding between the core and each layer of groove. The coupling mode theory of optical fibers was applied to analyze the two transmission characteristics of crosstalk and mode field area between bent six core optical fibers. The results show that the bending radius and groove have a significant impact on the crosstalk and mode field area of the optical fiber, respectively. After adding grooves, the crosstalk between fiber cores significantly decreases. Under different bending radii, the change in crosstalk between fiber cores is about 10 dB. At the same time, the change in mode field area under different layers of grooves is about 150 μm2.