We present a method for converting 1-D Maxwell equation into a linear system using the Multivariable Output Error State Space (MOESP) method, a subspace system identification method. To show the efficiency of the method, we first apply it to a set of ordinary differantial equations. Input and output from the equation set are computed by numerical methods and the obtained data is used for building the required matrices. An appropriate Single Input Single Output (SISO) linear system is estimated by MOESP algorithm for the equation at hand. The goal of the research is to build a low order linear state space system model for the Maxwell equation. On the other hand the order estimation for the system can be used in other way. For example, with this estimation one can determine an appropriate order for the physical system, for which one of the well-known model order reduction techniques can be used to obtain a reduced order model.