The present study investigates the effect of pellet deposition position on Li pellet-triggering edge localized modes (ELMs) in the EAST tokamak using a BOUT++ three-field MHD model with impurity effects considered. The present simulations focus primarily on Li pellet injection from the outer mid-plane, in which the ablated material is deposited either on the pedestal top (PT) or within the steep gradient region (SR). Under the present modified model, the deposition within the SR is found to be more favorable for ELM triggering than the deposition on the PT. With the same ratio of the modified to unperturbed pressure at the peak deposition position, the SR deposition leads to earlier ELM onset and larger ELM sizes. These results are generally in agreement with previous studies (Li et al 2024 Nucl. Fusion64 086061), but are more physically reasonable. Additional simulations of injection from 40 cm above the mid-plane on the low-field side (L-Z40) are also carried out to test whether the drawn conclusion qualitatively is valid at other poloidal injection angles. Although geometric effects weaken the overall enhancement in pressure profile and delay ELM onset to some degree, the L-Z40 cases also show that the SR deposition is relatively more effective than the PT deposition. The present study indicates that pellet deposition position and impurity physics play a non-negligible role in ELM triggering, and also shows that the SR is a good deposition position for low-Z impurity pellets pacing ELMs in future devices.