In this study, based on magnetic tunable characteristics of nanoparticle magnetic fluid, we design the photonic crystals' defect-localized modes with a defect layer of nanoparticle magnetic fluids. The transmission spectrum of one-dimensional photonic crystals with a defect layer of nanoparticle magnetic fluid is calculated numerically using the transfer matrix method. The results indicate that the wavelength of defect localized modes moves to short wave with the increasing of magnetic field intensity. The maximum variation is 7 nm. When the thickness deviation of defect layer is in the range of 5 nm, the variation of the wavelength is 6 nm. The bandwidth of the defect localized modes is 0.2 nm and its quality factor is of the order of 103. Therefore, the variation of the wavelength of defect-localized modes, which is caused by the thickness deviation of a defect layer, could be compensated by changing the magnetic field. In this study, the defect-localized modes with a certain wavelength are realized.