Abstract: To investigate the possibilities of employing speckle patterns alterations, to be noticed in an emerging light spot from step index multimode optical fiber, due to outer perturbation for sensing purposes; first order moment statistical feature is used to design the optical fiber sensors of statistical mode. The experiments of optical fiber sensor of statistical mode are performed for different applied weights and the related images were captured by using a CCD camera. First moment statistical feature is taken out from these images after suitable image processing. A definite weight was applied on a fiber optic in which beams of a He-Ne laser were propagating then variations in speckle patterns were noticed. To achieve the application of effective weight on the fiber optic, a part of load application which has some ridges positioned between two parallel flat plates was employed. The achieved results illustrated that when fiber optic was positioned so that corrugation of bending was made by the application part of load (by means of ridges)and when loads were applied on the optical fiber, the difference in first order moment increased as weight was applied. The effect of area size of contact between fiber optic and ridges was set by employing some different preparations for the application part of load. With these results and by using statistical mode feature it was assured that speckles observation in a light spot emerging from a fiber optic can be used for realization of fiber optic sensor having statistical mode for sensing the application of load applied on the fiber optic. For enhancement of load application effects, appropriate arrangements were used with ridges having convenient dimensions which are alternately organized against the fiber optic.