The fiber Bragg gratings with triangular spectrum will have important applications in fiber sensing areas. The coupling coefficient distribution along the length is acquired for triangular spectrum fiber Bragg gratings by using genetic algorithms synthesizing. The simulation results show that the triangular fiber Bragg gratings can be realized; the reflection bandwidth can be adjusted by chirping of the grating; uniform fiber Bragg gratings have small reflection bandwidth, while the gratings with chirped period have larger reflection bandwidth, which is similar to the chirp. A triangular fiber Bragg grating with 0.77 nm base width of reflection spectrum is fabricated experimentally by using a scanning method.