Design of strain sensors by using two methods of MZM, two Separated Arms MZM and in-line MZM. The in-line MZM is simple and lower cost than separated arms MZM, this in-line MZM is designed by splicing SMF with MMF. Four lengths of MMF have been used which are (90mm, 80mm, 70mm and 50mm).Weights from (50 to 2000) g are used and placed on MMF. The sensitivity calculated of these MMF length have been (7.6pm/µ , 6.15pm/µ , 5.45pm/µ and 4.615pm/µ ) respectively, best sensitivity was obtained with length of MMF is 90 mm.