Abstract: Fiber-optic communication has been growing at a phenomenal pace over the past twenty years, so rapidly,in fact, that its impact is increasingly felt in nearly all aspects of communication technology.Transmission properties of tapered fiber are discussed in this paper.The transmission efficiency of the tapered fiber is measured. By the scalar wave equation and Gaussian approximation,transmission properties of tapered fiber are analyzed, and the power losses caused by taper angle are also calculated. The distribution of power in the fiber versus the normalized frequency, the spot size versus the core diameter, the data sheet of transmission efficiency with coning angle, and the transmission efficiency T versus the tip diameter are all discussed in this paper. According to a sequence of coning angle,the curve of transmission efficiency versus coning angle is given. From the experiments and analyses, it could come to the conclusion that the bigger the taper angle is, the higher the transmission efficiency becomes.