To develop a model for predicting postoperative axial length (AL) in children undergoing cataract surgery younger than 2years of age. The Eye Hospital of Wenzhou Medical University, Hangzhou, China DESIGN: Retrospective study. Children were included only if AL data were available before surgery and at least 1year after surgery. Eyes were divided into pseudophakic, aphakic, and unaffected eye groups. Variables that could influence axial growth were analyzed and a multivariable generalized estimating equation regression model was developed to predict postoperative AL. 333 eyes from 190 patients were included. We observed a logarithmic linear correlation between age and AL in the unaffected eye group, AL = (2.7924 × log of age in months) + 17.607, R2 = 0.6596. Meanwhile, The GEE model of eyes with cataracts can be written as follows: Postoperative AL = 6.408 + 0.611 × (baseline AL) + 0.007 × (baseline age) - -0.006 (baseline age) × (age at follow-up) - -0.391 × coefficient of surgery. The ages were recorded in months, the ALs were recorded in millimeter. The assessment of AL is one of the most important parts of successful postoperative management in congenital cataract patients. This study established an AL estimate formula for children aged ≤ 2years with congenital cataract who underwent cataract surgery. This model theoretically could be used to predict individual future AL for child undergoing cataract surgery.