AIM: To determine the teaching effects of a real-time three dimensional (3D) visualization system in the operating room for early-stage phacoemulsification training. METHODS: A total of 10 ophthalmology residents of the first-year postgraduate were included. All the residents were novices to cataract surgery. Real-time cataract surgical observations were performed using a custom-built 3D visualization system. The training lasted 4wk (32h) in all. A modified International Council of Ophthalmology’s Ophthalmology Surgical Competency Assessment Rubric (ICO-OSCAR) containing 4 specific steps of cataract surgery was applied. The self-assessment (self) and expert-assessment (expert) were performed through the microsurgical attempts in the wet lab for each participant. RESULTS: Compared with pre-training assessments (self 3.2±0.8, expert 2.5±0.6), the overall mean scores of post-training (self 5.2±0.4, expert 4.7±0.6) were significantly improved after real-time observation training of 3D visualization system (P<0.05). Scores of 4 surgical items were significantly improved both self and expert assessment after training (P<0.05). CONCLUSION: The 3D observation training provides novice ophthalmic residents with a better understanding of intraocular microsurgical techniques. It is a useful tool to improve teaching efficiency of surgical education.