Abstract: To investigate the wound effectiveness of cross-medium bullets, gelatin was chosen as a simulated human target. The numerical simulation of the penetration process of the designed 7.62mm multi-environment bullet into the simulated target was conducted using LS-DYNA software. The motion of the bullet and the changes in the target cavity were analyzed. By utilizing a three-degree-of-freedom rigid body motion model, the theoretical variations of bullet motion were obtained. Simultaneously, the penetration experiment was carried out using multi-parameter synchronous measurement techniques. The results showed that the numerical simulation matched well with the experimental observations, effectively reproducing the penetration process and the wound effects of the multi-environment bullet. The theoretical model exhibited small errors compared to the experimental results and accurately predicted the motion characteristics of the bullet in the target. By employing a cavity structure, the stability of the bullet's motion across different media was improved. Compared to the traditional 56-type 7.62mm rifle bullet, the designed bullet demonstrated longer stable flight time, greater distance, slower velocity decay, smaller deflection angle during tumbling phase, and comparable maximum cavity, permanent cavity, and energy transfer efficiency. It also exhibited a certain killing effect on the target. The research findings enrich the design theory of bullets and provide data support for the optimization design of new lightweight ammunition.