Pseudo-ferroelectric transistors have attracted particular interest owing to their applications in the non-volatile memories and neuromorphic circuits; however, it remains to be explored in the limit of few-layer devices. Here we reveal a pseudo-ferroelectric phenomenon in the ultrathin graphene/black phosphorene (G/BP) heterostructure by first-principles calculations. Putting forward an excitation-assisted mechanism, the ferroelectric-like hysteresis loop can be explained by a combined effect of the external electric fields dependent bipolarity and anisotropy in the G/BP heterostructure. Considering the build-in electric field, the bipolar behavior results in the multistate effect of the G/BP heterostructure when modulating the applied electric field. The anisotropic hybridization caused by the susceptible Dirac electrons in graphene and the large in-plane anisotropy in BP provides the interfacial states, which trap excitations and stabilize the multistate. The pseudo-ferroelectric behavior should be useful for interpreting transport experiments in gated G/BP devices and exploring its applications in memories or synaptic devices.