The Kink phenomenon presented in the I-V output characteristics of CMOS devices at low temperature (T<50K) is studied. The impact of Kink effect on CMOS readout integrated circuits for cryogenic operation is examined. The output characteristic of source follower, the gain characteristic of common-source amplifier and two-stage amplifier all exhibit severe nonlinearity resulted from the Kink effect. Based on the analysis of Kink effect problems, several solutions are proposed for the design of CMOS readout integrated circuit operated at low temperature. The improvement is verified through the simulation.