A novel material has been developed by electrospinning of thermoplastic polyurethane (TPU) ultrafine fibre webs containing boric acid (BA). The chemical characterization of the TPU/BA fibrous webs is determined by the energy dispersive spectrometer and the Fourier transform infrared spectroscopy. The morphologies and thermal properties of the webs obtained are investigated by scanning electron microscopy and the differential scanning calorimeter respectively. The electrospun fibrous webs’ air permeability performance and thickness are also measured. The morphologies of TPU fibrous webs change slightly by adding BA, and the fibre structures are maintained. The results obtained demonstrate that the electrospun TPU/BA fibrous webs may have a wide variety of potential applications in protective textiles and high-performance filters.