In order to improve the inspection accuracy and reduce misjudgment rate for the solder joint quality inspection in an automatic optical inspection system, a pseudo solder joint inspection method for lead-free solder joints in a Printed Circuit Board(PCB) was proposed based on analyzing the solder joint image acquired by a 3-color LED structure illuminator and a color 3-CCD camera. Three steps were used to detect the pseudo solder joints. Pseudo solder joints were inspected firstly by the center of gravity method after positioning the solder joints and its components. Then, the regions of solder joints and components were figured out based on their edge, and the area method was used to inspect pseudo solder joints. Finally,the missed pseudo solder joints were inspected by the proposed color grad method. The experiment results show that the proposed method composed of the center of gravity method, area method and the color grad method can inspect the pseudo solders effectively, and the inspection accuracy can reach 99.2%.