The present disclosure provides an omni-directional terrain crossing mechanism, including a transformable mechanism with a plurality of claw wheels, in order to be capable of fast moving on the flat ground or in uneven terrain environments. The omni-directional terrain crossing mechanism includes a first body and a second body. Each of the first body and the second body includes at least one pair of claw wheels. Moreover, the omni-directional terrain crossing mechanism is capable of transforming one pair of first claw wheels of the first body and one pair of second claw wheels of the second body into a pair of complete wheels. Consequently, as compared with the existing mobile machines, the omni-directional terrain crossing mechanism in the present disclosure is capable of moving in various challenging terrain environments.