In this work, multifunctional alpha-Fe2O3@dopamine core-shell nanocomposites consisting of alpha-Fe2O3 core surrounded by a thin dopamine (DA) shell have been successfully fabricated. The crystal structure, surface morphology and optical properties of the samples were determined by XRD, SEM, TEM and UV-vis, respectively, indicating that the presence of thin DA shell could affect the optical properties of Fe2O3 nanostructures. When it was incubated with NIH3T3 cells and injected in living body, the concave shape Fe2O3@dopamine nanocomposites exhibited the highest cell viability (94.6% within 16 h), and harmless to the living body. Moreover, the concave shape Fe2O3@dopamine nanocomposites also displayed the highest image contrast and distinguishability (3.74 times of control group, and 1.5 times of purchased Au nanoparticles). Thus, alpha-Fe2O3@dopamine core-shell structures are promising candidates for precise photoacoustic imaging and therapeutic process.