In order to synthesize the targeting drug carrier system, magnetic chitosan-5-fluorouracil nano-particles were prepared by using 5-fluorouracil (5-Fu) as model drug, Fe_3O_4 nano-particles as kernel, chitosan as enveloping material and glutaraldehyde as cross linking agent through ultrasonic technique. The morphology of the magnetic chitosan-5-Fu nano-particles was observed with a transmission electron microscope(TEM). The results showed that magnetic chitosan-5-Fu nano-particles were prepared in spherical structure with a size range of 50-60 nm. The delivering capacity and drug releasing properties of magnetic chitosan-5-Fu nano-particles were investigated by UV-vis spectrum analysis. The results showed that the loading capacity was 13.4% and the cumulative release percentage in the phosphate buffer (pH=7.2) solutions was 68% in 30 h. These data indicate that the wrapped drug of magnetic chitosan-5-Fu nano-particles was slowly-released. The magnetic response of magnetic chitosan-5-Fu nano-particles was studied by UV-vis spectrometer to detect the changes of solution absorbance. Without external magnetic field, the nano-particle deposition rate was slow. When being subjected to 8 mT magnetic field, the particle sedimentation rate was increased rapidly. The results showed that magnetic chitosan-5-Fu nano-particles have a magnetic stability and strong targeting characteristics.