This paper presents a novel network decomposition method that can detect faults of linear analog integrated circuit (IC) in network. The nodal admittance matrix (NAM) of linear analog IC is a function of its internal component values, which can be used for fault detection. However, it is difficult to obtain the NAM of linear analog IC in network. We propose a network decomposition based method to calculate the NAM of the IC under test in network. The IC under test is fault free, if its NAM lies inside the tolerance limit. Otherwise, it is faulty. The effectiveness of the proposed method is validated through benchmark circuits.