This paper describes a switched-opamp based design of ROIC for IRFPA′s low power application.A column opamp using this technique to manage power is realized to switch between ‘sleep’ and ‘wake up’ operation mode,which only operates properly at the time it is selected.This structure level optimization method save opamp′s operation time and is suitable for low power dissipation systems for it significantly reduces the power dissipation of ROIC.Two options of readout timing are designed for a 4×4 ROIC′s transient analysis.This design saves 83% power of column opamp at most during readout time as compared with the existent one.