Abstract: Recently, Single-Term Haar Wavelet series (STHW) is introduced to overcome the difficulties in solving some singular system problems. Preliminary experiments have shown that this method is usually more efficient than the other methods. In this study, STHW is developed to approximate the solution of second order singular system problems in the Ordinary Differential Equations (ODE). These types of problems arisen in science and engineering field frequently. The obtained discrete solutions using the STHW are found to be very accurate and are compared with the exact solutions of the second order singular system problems in the ODE. The results obtained show that the STHW is more useful for solving second order singular system problems in the ODE and the solution can be obtained for any length of time.