An adjusting mechanism for the handle position of a bicycle includes an upper cover (2) and a lower cover (3), which clamp the handle, and a handle vertical pipe (5) fastened on the front fork by a retaining mechanism. One side of the upper cover and one side of the lower cover for clamping the handle are connected with each other, and the other sides can be interlocked by an independent retaining mechanism. The top of the handle vertical pipe is provided with steps (6), and the lower cover is sleeved outside the handle vertical pipe and arranged below the steps at the top of the handle vertical pipe. As the lower cover is sleeved outside the handle vertical pipe and arranged below the steps at the top of the handle vertical pipe, the handle vertical pipe can be tightly fixed on the front fork by the retaining mechanism, furthermore, the handle position can be repeatedly adjusted without influencing rigidity between the front fork and the handle, thus the bicycle becomes more comfortable and has better safety performance. Meanwhile, by loosening the retaining mechanism, the whole handle system can rotate relative to the vertical pipe. When the bicycle is not in use, the handle can be rotated downward to the direction parallel to the body of the bicycle, thereby reducing space occupied by the bicycle.