Abstract: Electromagnetic ion cyclotron instability (EMIC) is a significant plasma instability driven by ion temperature anisotropy, widely observed in diverse spatial and experimental plasma environments such as Earth's magnetosphere, planetary magnetospheres, solar wind, and magnetic confinement fusion devices. As a typical anisotropy-driven instability, EMIC exerts a crucial influence on energy transport and particle heating processes in magnetized plasmas. Among these, ion cyclotron resonance heating is recognized as a key mechanism for achieving efficient plasma heating. This study employs a one-dimensional three-component particle-in-cell (PIC) method to numerically investigate the nonlinear evolution of EMIC under periodic boundary conditions. The Boris algorithm advances particle motion, while the fast Fourier transform (FFT) is utilized for diagnosing and analyzing the electromagnetic field spectrum. Numerical results indicate that increased ion temperature anisotropy significantly enhances the instability growth rate while altering the wave spectrum structure and dispersion characteristics. As anisotropy intensifies, ion vertical energy progressively converts to parallel energy, revealing the energy coupling mechanism during wave-particle interactions. This study provides important insights for deepening the understanding of ion heating and acceleration mechanisms in both space and laboratory plasmas.