Based on the coupled mode theory, by using the reversely recursive transmission matrix method, the switching characteristics of the λ/4 phase-shifted fiber grating and the influence of introducing chirp on the switching characteristics have been numerically studied when the reflection on the transmission facet is taken into account. For coherent superposition reflection strengthening, it can reduce the threshold switching energy of the λ/4 phase-shifted grating, but the switching contrast will decline. With the introduction of negative chirp in λ/4 phase-shifted grating, the switching contrast is greatly improved, but the bistable threshold switching energy will increase. With the introduction of positive chirp in λ/4 phase-shifted grating, the switching threshold can be further reduced, but the switching contrast will decline. The bistable loop width will be influenced greatly by the chirp.