To overcome the limitations of traditional acoustic metasurfaces in dynamic wave manipulation, this study proposes an active, tunable, and ultra-thin acoustic coding metasurface based on a piezoelectric composite structure (PCS) unit. Conventional designs mostly rely on static structures such as space-coiling channels or Helmholtz resonators, whose acoustic functionality is fixed once fabricated. Although mechanical tuning methods have been introduced to adjust the acoustic response, they generally suffer from slow response, complex structure, and mechanical wear. Digital coding metasurfaces, even those conceptually derived from electromagnetics, largely adhere to a paradigm of fixed geometric units. This fundamental constraint escalates design complexity and curtails reconfigurability. Our design realizes efficient, real-time, and multifunctional dynamic reconstruction of acoustic fields through an electronic tuning mechanism. The core PCS unit integrates a piezoelectric composite patch and dual Helmholtz resonators, forming an ultra-thin structure with a thickness of only about 1/34 of the operating wavelength. By simply switching the external circuit between open and short states, the unit can achieve instantaneous and reversible switching between the "0" and "1" coding states without any mechanical movement, producing a phase difference of about 0.9π at the specific frequency while keeping the transmission amplitude stable. An equivalent circuit model is established to reveal the resonant frequency tuning mechanism dominated by electro-acoustic coupling, which provides theoretical support for the coding reliability. To validate the performance, we realized three types of acoustic field manipulation through coding sequence programming: 1) A tunable coding Fresnel lens that achieves precise convergence of the acoustic energy at a preset focus, with a full width at half maximum of only about 0.75 wavelengths, and off-axis focusing is also demonstrated by reprogramming; 2) A sound beam splitting function implemented using a 2×2 unit array and coding sequences such as "00/00", "01/01", and "01/10", which successfully generates single, dual, and quadruple far-field beam distributions, respectively; 3) Acoustic vortex regulation using a binary phase profile generated by an 18×18 array, which excites vortex beams with topological charges of 1, 2, 3, and 4, and enables precise control including off-center focusing. Simulation results show that the metasurface achieves accurate dynamic control of the acoustic field electronically, with advantages such as an ultra-thin size, fast response, high integration, and no mechanical wear, effectively overcoming the drawbacks of conventional devices including single function, slow response, and poor reconfigurability. This study provides an innovative technical solution for the new generation of tunable acoustic devices, with promising application prospects in high-capacity acoustic vortex communication, acoustic invisibility, directional sound transmission, and other cutting-edge fields.