In this paper, a new method is proposed to fabricate bending insensitive Bragg fiber gratings using femtosecond laser with slit mask. Designed central wavelength of FBG is 1550 nm, its reflectivity is greater than 98 %, bandwidth is 0.22 nm, temperature sensitivity is 0.0137 nm/°C, strain sensitivity is 0.001 nm/με, and bending sensitivity is -3.1 pm/mm. Test results indicate that reflectivity is 99.25 %, and bandwidth is about 0.222 nm. Central wavelength of FBG is 1550.02 nm, bending sensitivity is -3.12 pm/mm, temperature sensitivity is 0.01368 nm/°C, strain sensitivity is 0.00098 nm/με. These testing results are consistent with simulations. This method is suitable for manufacturing bending insensitive fiber Bragg gratings.