The objective of this paper is to design and implement a single-stage fly-back converter with power factor correction. The input voltage is 110 V/AC and output voltage is 12 V/DC. The basic principle of the single-stage fly-back converter is analyzed, and then the design and implementation of this converter are presented. For the implementation, the control IC of NCP1651 G is used as controller. Experimental results show that the power factor is higher than 0.85 and the efficiency is greater than 80%. These results fully confirm the design and implementation.