A flexible optical measuring device comprises an optical distance measuring module, an optical fiber adapter and an optical coupling module. The optical distance measuring module comprises a light source, an optical receiver and a computing unit. The optical fiber adapter is disposed and connected between the optical distance measuring module and the optical coupling module. The optical coupling module comprises a first optical fiber, a two-in-one optical coupler, a detector and a second optical fiber. A measuring beam is emitted from the light source and reaches the detector. The measuring beam then passes through the detector to the object and forms a reflected beam which is reflected back to the detector, then enters the second optical fiber and passes through the optical receiver and the optical receiver outputs a measurement signal. The computing unit calculates the distance between the object and a terminal of the detector accordingly.