Abstract: The organic piezoelectric sensor prepared by electrospinning is better flexibility, light weight and breathability than the traditional pressure sensor, which has attracted much attention in the field of wearable sensor research. In this paper, a method of preparing BiCl₃/poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) composite film by electrospinning was proposed, and the flexible piezoelectric sensor was designed and prepared with the composite film as the functional layer. After a certain amount of BiCl₃ is added, the scanning electron microscope analysis shows that the average diameter of the fiber increases from 619 nm to 1158 nm, and the surface becomes smoother. The X-ray diffraction pattern confirms that β phase content of the composite film has been significantly improved. The piezoelectric response testing results show that the open circuit peak-to-peak voltage (V_oc) and short-circuit current (I_sc) of P(VDF-TrFE) composite films with 2wt%BiCl₃ are 16.8 V and 164 nA. Compared with pure P(VDF-TrFE) piezoelectric film, it is obviously improved 2.15 and 2.24 times. The pressure sensing testing results show that the piezoelectric film is good linear output characteristics under the pressure of 1.28 N. A flexible wearable force sensing keyboard was designed with this film, which could collect fingers pressing force and duration time. And it provides a reference solution on smart fabrics such as flexible keyboard applications.