The composite nanofibrous membranes were fabricated by the growth of CaP crystals on electrospun gelatin nanofibres to mimic both the physical architecture and chemical composition of natural bone extracellular matrix (ECM). The amount of CaP crystals formed on the membranes increased with the increment of CaCl2 concentration, in which these crystals were also observed on the inner side of membrane. The energy dispersive X-ray spectroscopy (EDX) mapping analysis confirmed a homogenous distribution of CaP crystals on the membranes. Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray diffraction (XRD) results clearly revealed the formation of apatite phase on the GEL-CaP25 membrane. On the other hand, biphasic crystals of apatite and CaCO3, or apatite and tricalcium phosphate (TCP) were produced on the GEL-CaP05 and GEL-CaP50 membranes. The Ca/P molar ratios of crystals obtained from the XPS data were 2.03, 1.68 and 1.56, which depended on the CaCl2 concentration. Higher amount of CaP crystals significantly accelerated the deposit rate of bone-like apatite on the surface of composite membrane, meaning to the improved in vivo bone bioactivity.