We present the 850~$\mu$m polarization and $\ceo~(3-2)$ molecular line observations toward the hub region of X-shaped nebula in the California molecular cloud using SCUBA-2/POL-2 and HARP instruments mounted on the JCMT. The 850~$\mu$m emission shows that the hub region includes two elongated filamentary structures (referred as Fil1 and Fil2 in the study) having chains of regularly spaced dense cores. We measured the mass per unit length of filament, and found that the two filaments are thermally super/transcritical but totally subcritical if nonthermal turbulence and magnetic field are considered. The mean projected spacings ($\Delta \bar S$) of cores in Fil1 and Fil2 are 0.20 and 0.19~pc, respectively. $\Delta \bar S$ in Fil1 is smaller than $4 \times$filament width expected in the classical cylinder fragmentation model while that in Fil2 is consistent. The large scale magnetic field orientations shown by Planck are perpendicular to the long axes of Fil1 and Fil2, while those in the filaments obtained from the high resolution polarization data of JCMT are found to be disturbed but found to have longitudinal orientations. Using the Davis-Chandrasekhar-Fermi (DCF) method, we estimated the magnetic field strengths ($B_{\rm pos}$) of filaments which are 180 and 110~$\mu$G. We calculated the gravitational, kinematic, and magnetic energies of filaments, and found that the portion of magnetic energy is about 60\% in both filaments. We propose that the dominant magnetic energy may lead the filament to be fragmented into aligned cores as suggested by \citet{tang2019}, and the shorter core spacing in Fil1 can be due to the projection effect via inclined geometry of filament or the non-negligible, longitudinal magnetic fields in the filament.