A random access method and random access system for a terminal in a high-speed mobile environment are provided. Wherein, the method comprises: selecting a random access preamble format according to a preset cell coverage radius target value; judging whether using a restricted set of cyclic shift quantities pre-configured satisfies a requirement of the cell coverage radius target value under the selected random access preamble format; if not satisfying, selecting a cyclic shift quantity which satisfies the requirement of the cell coverage radius target value from a unrestricted set of the cyclic shift quantities pre-configured; and generating a random access signal according to the cyclic shift quantity and a pre-configured mother code, and performing access using the random access signal. Through the above-mentioned technical scheme, the embodiment of the present document provides a more perfect random access method and random access system for a terminal in a high-speed mobile environment.