Manual assembly is still an important method for complex products. There are various manual assembly errors due to distinct factors under changing production environments. Information assistant is an efficient way for preventing human errors during manual assembly operations. Augmented reality can superimposes the information in front of the users’ view to facilitate their work. Offline training and onsite assistant based on augmented reality were research hotspots in academic and industry. In this paper, the human assembly errors in literature were collected and analyzed from human reliability analysis and skill-rule-knowledge behaviour model aspects. The information characteristics of traditional paper manual, electronic file manual, 3D manual and augmented reality manual for assembly assistant were discussed. Augmented reality based information presentation for error prevention was proposed for on-site manual assembly assistant. Seven typical assembly operations were identified and classified to different skill-rule-knowledge levels for on-site workers. The functions and visual elements of augmented reality for error-less assistant were discussed.