The noise performance of optoelectron coupled devices (OCDs) has been analyzed firstly from the rate equations including Langevin noise sources (C. Harder, J. Katz, S. Margalit, J. Shacham, A. Yariv. IEEE J Quant Electron 1982; QE-18(3):333-7). The noise equivalent circuit of OCDs has been presented in this paper and is used to explain the noise spectrum measurement results of OCDs. Then three noise reliability indicators used to estimate quality and reliability of OCDs are given. These indicators are general and convenient for the direct industrial application for OCDs and other semiconductor devices.