The effects of low-temperature deuterium annealing on the reduction of dark currents in the CMOS active pixel sensor (APS) have been investigated. Experimental results reveal that deuterium annealing is more effective in reducing dark currents of the CMOS APS than conventional forming gas annealing, because it shows the enhanced passivation efficiency of the interface traps located in the sidewall of the shallow trench isolation. From the characterization results of test structures, it is found that the dark currents generated from the photodiode and floating diffusion node region can be reduced more effectively by using the deuterium annealing process.