Since nonwoven fabrics are made of irregular assembly of fibers, it is difficult to predict the mechanical properties of the fabrics from those of their constituent filers and their structure. In this paper, we propose a simulation algorithm for mechanical properties of spun-bonded nonwoven fabrics from the fiber properties and the structure of the fabrics. The algorithm requires simplified structure of spun-bonding structure which can be easily determined by microscopic image and fiber modulus. It is assumed that the number of fibers connecting bonding sites can represent the structure of the fabrics, including the information of fiber orientation in a discrete manner.