Safety issues of lithium-ion battery under mechanical abuse have attracted worldwide attention due to its high uncertainty and high risks, following by the rapid increasing of market share for lithium-ion battery-driven smart products. In this work, the safety behavior of a pouch battery under mechanical abuse conditions is numerically investigated using a simultaneously coupled mechanical-electrochemical-thermal model. The short-circuit and electrochemical-thermal responses of lithium-ion batteries under various mechanical abuse conditions are successfully predicted and compared. The main impact factors, including the state of charge (SOC), indenter shape and size, and loading displacement, are systematically studied and analyzed. The comprehensive parametric studies show that the battery is in a more dangerous state under higher SOC, identify the critical distinction of the short-circuit behavior between sharp indenter and blunt indenters for battery, and explain the discrepancies in the repeated mechanical abuse tests. These conclusions provide theoretical insights for understanding the failure mechanism of lithium-ion batteries under mechanical abuse, and technical support for the safety design of battery packs.