The present disclosure relates to a method and apparatus for searching for a light-weight model through the replacement of a subnetwork of a trained neural network model. The method of searching for a light-weight model includes a preprocessing step of extracting a subnetwork from an original neural network model, constructing a mapping relation between the subnetwork and an alternative block corresponding to the subnetwork by extracting the alternative block from a pre-trained neural network model, and generating profiling information including performance information relating to the subnetwork and the alternative block, and a query processing step of receiving a query, extracting a constraint that is included in the query through query parsing, and generating the final model based on the constraint, the original neural network model, the alternative block, the mapping relation, and the profiling information.