The technique of optical fiber sensor has been of great interest, as it has various advantages. In this paper a novel optical fiber sensor has been developed based on Michelson interference principle. Furthermore we describe a non-contact method for precision measurement of the surface tension on fluids by this sensor. The experimental results are more precise than that of conventional method. The system is immune to environment perturbation, the configuration is simple and the resolution is high. The presented method overcomes the disadvantages of conventional method, improves measuring precision, and expands the range for application of optical fiber sensors.