An optical touch device includes at least one light source, a first image capturing module, a second image capturing module and a control module. The at least one light source is disposed outside a display unit for emitting light to an object. The first image capturing module and the second image capturing module respectively capture images of an object, and a relative position between the first image capturing module and the second image capturing module can be adjusted. The control module is coupled to the first image capturing module and the second image capturing module for calculating a coordinate value of the object according to the images of the object captured by the first image capturing module and the second image capturing module and the relative position between the first image capturing module and the second image capturing module.