The boron-coated ionization chamber is widely used in neutron detection for reactor external nuclear instrumentation systems due to its strong radiation resistance, long service life, high-temperature and humidity tolerance, and reliable performance. These ionization chambers find extensive applications in nuclear energy, radiation protection, and radiological medicine. The electrical signals in boron-coated ionization chambers are primarily generated by gamma rays and neutrons, with gamma noise significantly reduced through compensation techniques. However, due to potential compensation errors, gamma noise may still affect the neutron signal. Under low neutron flux and high gamma noise conditions, traditional boron-coated ionization chambers exhibit a low signal-to-noise ratio, leading to neutron signals being obscured by gamma noise, making accurate neutron flux measurements difficult. To enhance the neutron detection efficiency and sensitivity of boron-coated ionization chambers, this study proposes a novel design that incorporates a multilayer boron-coated cylindrical structure based on a parallel-plate gamma compensation ionization chamber. The new structure significantly increases the effective boron-coated volume per unit volume, replacing the traditional method of coating boron compounds only on electrode surfaces, thereby improving neutron detection efficiency. Using combined simulations with Geant4, Garfield++, and SRIM, the structural parameters of the ionization chamber were optimized, and the neutron detection efficiency before and after improvement was calculated. Simulation results demonstrate a significant enhancement in neutron detection efficiency with the improved boron-coated ionization chamber, providing a promising and reliable solution for practical neutron detection applications.