Based on the low-coherence interferometric principles, a cost-effective all-fiber Mach-Zehnder multiplexing system is proposed and demonstrated. The system consists of two interferometers: sensing interferometer and demodulation interferometer. By scanning an optical tunable delay line back and forth constantly with a stable speed, sensing fibers with different optical paths can be temporal interrogated. The system is experimentally proved to have a high performance with a good stability and low system noises. The multiplexing capacity of the system is also investigated. An experiment of measuring the surrounding temperature is carried out. A sensitivity of 12 μm/℃ is achieved within the range of 20 ℃ to 80 ℃. This low cost fiber multiplexing system has a potential application in the remote monitoring of temperature and strain in building structures, such as bridges and towers.