The ion cyclotron (IC) parametric decay instability (PDI) of lower hybrid (LH) waves with different plasma densities, LH power levels and magnetic configurations is investigated on the EAST tokamak. The non-linear behaviors of PDI are well documented using radio frequency (RF) loop probes, which measure the frequency spectrum of LH waves. It is observed that the IC sidebands grow significantly with the plasma density and LH power. An effective method to mitigate PDI activities in high-density H-mode plasmas by adopting a favorable magnetic field Bt (namely, the ∇B drift of ions toward the primary X-point) is found. Numerical calculations are performed by solving the parametric dispersion relation to explain the observed growth of IC sidebands. The simulated results highlight that multiple passes across the scrape-off layer (SOL) are necessary to take into account for evaluating the amplification factor of the sideband waves in the weak damping regime. Finally, the impact of PDI on the LH current drive (LHCD) efficiency and the implications of this study to future tokamak experiments are discussed.