A clamping device includes first and second clamping members. Each of the first and second clamping members has a handle and a jaw. A bend is formed between two ends of the jaw of the first clamping member, and a first angle between the jaw and the handle of the first clamping member is smaller than 180°. Another bend is formed between two ends of the jaw of the second clamping member, and a second angle between the jaw and the handle of the second clamping member is equal to the first angle. The clamping device can be used to clamp a pipe. When the second clamping member is moving from a release position to the clamping position, two clamping portions respectively of the jaws remain parallel to each other such that force is evenly applied to two sides of the pipe.