Objective To prepare liquid fluorocarbon nanoparticles carrying HMME-Gd (HMME-Gd-PFPNPs) and observe the effect of ultrasound/MRI imaging capability in vitro. Methods Lipids cholesterol, hematoporphyrin monomethyl ether gadolinium (HMME-Gd) and perfluoropentane (PFP) were used as raw materials to prepare nanoparticles by membrane hydration and emulsification. The general physical properties were measured by optical microscopy, transmission electron microscopy and laser confocal microscope. The size and surface potential were analyzed by particle size analyzer. The encapsulation efficiency of HMME-Gd in HMME-Gd-PFPNPs was determined by UV-vis. The ultrasound (US)/magnetic resonance imaging (MRI) capability of HMME-Gd-PFPNPs was observed in vitro. Results HMME-Gd-PFPNPs were successfully prepared, which were regular in shape and uniform in size. They showed a black spherical structure under transmission electron microscopy. The size of HMME-Gd-PFPNPs was (250.27 ± 11.9) nm, the surface potential was (-26.17 ± 0.45) mV, and the encapsulation efficiency of HMME-Gd was (84.7 ± 0.35) %. As the concentration of HMME-Gd-PFPNPs increased, the MRI signal was significantly enhanced in vitro. Under low intensity focused ultrasound (LIFU) irradiation, the US imaging signal was significantly enhanced in vitro, which was positively correlated with the intensity of LIFU. Conclusion The liquid fluorocarbon nanoparticle contrast agent carrying HMME-Gd was successfully prepared and can be used for US/MRI dualmodal imaging in vitro.