Phosphorene has great potential in many applications. Here in this work, we succeed in exfoliating phosphorene directly in water by using sonication and microwave without additives, wherein violent oscillation generated by sonication facilitates intercalation of water into black phosphorus interlayers, and then the microwave further exfoliates the black phosphorus into phosphorene. The result demonstrates that this exfoliation method offers outstanding exfoliation efficiency. More importantly, the phosphorene dispersions exfoliated by our method may be directly used for future applications development.