A strain and temperature discrimination Sagnac interferometric fiber sensor is proposed and demonstrated experimentally. A segment of polarization maintaining fiber (PMF) is sandwiched between the multi-mode fiber (MMF) and twin hole fiber (THF) to build a sensing component. Then proposed MMF-PMF-THF fiber configuration is connected to a 3 dB optical fiber coupler to construct a Sagnac loop. The experimental results have demonstrated that the fringe contrast reaches up to 22.3 dB. The strain and temperature sensitivities are 43 pm/με and −1.36 nm/0C respectively. The temperature error and strain error are ± 0.77 °C and ± 24.5με respectively.