Flexible piezoelectric sensors combine the advantages of low cost, flexibility and multifunctionality, and show great market prospects. However, achieving efficient electromechanical conversion remains a challenge for piezoelectric sensors. Therefore, selecting piezoelectric materials with superior performance is crucial for enhancing the output characteristics of flexible piezoelectric sensors. In this study, polyvinylidene fluoride (PVDF)/MXene/poly(methyl methacrylate) (PMMA) piezoelectric composite films for flexible piezoelectric sensors were prepared by electrostatic spinning technique. The content of β-phase in the PVDF composite fiber film reaches 94.2% due to the synergistic effect of PMMA and MXene. The synergistic effect of PMMA and MXene also effectively enhances the mechanical properties and piezoelectric output of the material. The sensors exhibit high sensitivity in the low voltage range (5.63 V/N), fast response and recovery times of 70 ms and 71 ms, respectively. The sensor is capable of recognizing small human movements, and can also be used for realtime monitoring of table tennis training. Its application contributes to the stable and accurate measurement of movement parameters, which can be applied in a variety of sports and fitness monitoring scenarios.