A mobile navigation system for guiding a moving vehicle toward a target point, comprising: a radar antenna carried by the moving vehicle, emitting a first sensing beam at a first time point and emitting a second sensing beam at a second time point later than the first time point; and a processing device electrically coupled to the radar antenna; characterized in further comprising: a first retro-directive antenna disposed at a first position; and a second retro-directive antenna disposed at a second position, which is at a side of the target point opposite to the first position, and has a specific distance from the first position; wherein the first retro-directive antenna and the second retro-directive antenna being configured to respectively receive the first sensing beam and return a first retro wave and a second retro wave corresponding to a direction of the first sensing beam; the first retro-directive antenna and the second retro-directive antenna being configured to respectively receive the second sensing beam and return a third retro wave and a fourth retro wave corresponding to a direction of the second sensing beam, and the processing device being configured to receive the first, second, third and fourth retro waves, and determining whether a moving direction of the vehicle needs to be adjusted or does not according to first, second, third and/or fourth distances that the first, second, third and fourth retro waves travel, respectively, and the specific distance between the positions of the first retro-directive antenna and the second retro-directive antenna. a radar antenna carried by the moving vehicle, emitting a first sensing beam at a first time point and emitting a second sensing beam at a second time point later than the first time point; and a processing device electrically coupled to the radar antenna; characterized in further comprising: a first retro-directive antenna disposed at a first position; and a second retro-directive antenna disposed at a second position, which is at a side of the target point opposite to the first position, and has a specific distance from the first position; wherein the first retro-directive antenna and the second retro-directive antenna being configured to respectively receive the first sensing beam and return a first retro wave and a second retro wave corresponding to a direction of the first sensing beam; the first retro-directive antenna and the second retro-directive antenna being configured to respectively receive the second sensing beam and return a third retro wave and a fourth retro wave corresponding to a direction of the second sensing beam, and the processing device being configured to receive the first, second, third and fourth retro waves, and determining whether a moving direction of the vehicle needs to be adjusted or does not according to first, second, third and/or fourth distances that the first, second, third and fourth retro waves travel, respectively, and the specific distance between the positions of the first retro-directive antenna and the second retro-directive antenna. a first retro-directive antenna disposed at a first position; and a second retro-directive antenna disposed at a second position, which is at a side of the target point opposite to the first position, and has a specific distance from the first position; wherein the first retro-directive antenna and the second retro-directive antenna being configured to respectively receive the first sensing beam and return a first retro wave and a second retro wave corresponding to a direction of the first sensing beam; the first retro-directive antenna and the second retro-directive antenna being configured to respectively receive the second sensing beam and return a third retro wave and a fourth retro wave corresponding to a direction of the second sensing beam, and the processing device being configured to receive the first, second, third and fourth retro waves, and determining whether a moving direction of the vehicle needs to be adjusted or does not according to first, second, third and/or fourth distances that the first, second, third and fourth retro waves travel, respectively, and the specific distance between the positions of the first retro-directive antenna and the second retro-directive antenna.