Objective To investigate refractive error and amblyopia in a large group of patients with congenital ptosis presented to a specialist at the ophthalmology center. Methods This was a hospital-based retrospective analysis conducted at Beijing Tongren Eye Center from May 2010 to December 2012. We evaluated the frequency of ametropia and amblyopia in 242 eyes of 187 patients between 3 and 12 years of age with congenital ptosis. The patients were classified according to the degree of ptosis: mild, moderate or severe ptosis. Statistical analysis was performed using a chi-square and t-test. Results In 242 ptotic eyes, the frequency of myopia, hyperopia and astigmatism was 16.9%, 62.8% and 31.1%, respectively. The overall incidence of amblyopia in ptotic eyes was 29.8%. The incidence of amblyopia was higher in severe ptotic eyes than in mild or moderate ptotic eyes (57.8% vs. 41.2%, χ2=4.046, P<0.05). Conclusion The incidence of ametropia and amblyopia was high in congenital ptosis. Furthermore, amblyopia was more frequent in severe ptotic eyes.