In this paper, an additive manufacturing process, named Magnetic Field-assisted Projection Stereolithography (M-PSL), is presented for applications such as fabricating magnetic field-responsive smart polymer composites. The 3D printed magnetic field-responsive smart polymer composite creates a wide range of motions, opening up possibilities for various new applications, like sensing and actuation in soft robotics, biomedical devices, and autonomous systems. In M-PSL process, a certain amount of nano- or micro-scale ferromagnetic particles is deposited into resin vat with a programmable microdeposition nozzle. Then a magnetic field is applied to direct the magnetic particles to the desired area. After that, digital mask images are used to cure particles in photopolymer with certain patterns. Important issues like magnetic particle movements, curing mechanisms, and manufacturing process planning are discussed. Two test cases, an impeller and a two-wheel roller, have been successfully fabricated for remote control under external magnetic field, showing the capability of printed smart polymer composites on performing desired functions.