Objective：In order to improve the sensitivity and specificity of magnetic resonance contrast agent (MRCA) in the diagnosis of lesion site, and to overcome the limitations of single positive(T1) contrast agent and negative(T2) contrast agent as well as achieve the accurate diagnosis of diseases, a Fe3O4-BSAGd nanoparticle contrast agent was prepared for simultaneous T1-T2 dual-mode magnetic resonance imaging. The imaging performance and biocompatibility were evaluated. Methods：The superparamagnetic Fe3O4 nanoparticles with an oil-soluble particle size about 6 nm were prepared by the high temperature pyrolysis method, and the paramagnetic bovine serum albumin-gadolinium complex(BSAGd) was modified on the surface by phacoemulsification, while giving paramagnetic Fe3O4 nanoparticles, water solubility and good biocompatibility. Finally, the morphology, hydrated diametar(HD), saturation magnetization, relaxation efficiency(r), in vitro T1 and T2 weighted imaging and cytotoxicity were characterized. Results：The Fe3O4-BSAGd nanoparticles had a diameter of 10 nm and HD of about 32 nm, and the dispersion was uniform and stable. Fe3O4-BSAGd had a saturation magnetization of 30.2 emu/g. Longitudinal (r1) and transverse (r2) relaxation rates were 6.30 mM-1s-1 and 287.08 mM-1s-1, respectively. In vitro dual-mode imaging results showed a significant T1-T2 imaging effect and a concentration-dependent effect. The results of cytotoxicity test showed that the Fe3O4-BSAGd had a better biocompatibility. Conclusion：The effect of in vitro T1 and T2 weighted imaging of prepared Fe3O4-BSAGd nanoparticles was excellent with a good biocompatibility, which lays the foundation for the next step in vivo imaging.