Abstract: An improved folding bicycle comprising a folding hinge mechanism as well as a set of foldable handle-bar and a collapsible seat structure. During normal use, the folding hinge mechanism is easily associated with multi-securing effect to ensure the safety of ride. While stored, it can be alternatively unlocked and separated manually, enabling the bicycle to be folded up for reducing the storing room. Furthermore, the set of handle-bar and saddle adjusting device can be used to simply adjust the dimensions of the bicycle to meet the requirement of any use.