We investigate the influence of nonlinear coupling to the coherence of a qubit in the pure dephasing model. The total system consists of a qubit and a bosonic bath, which have nonlinear coupling. It's shown that no matter how small the coupling constant is, the long time behavior of the coherence is significantly changed in the case of free induction decay (FID). Unlike that of linear coupling, the evolution of coherence dominated by the nonlinear coupling exhibits strong quantum effect even for high temperature.