The invention discloses a current transformer engineering model building method based on a transient large current testing technology. The method comprises the following steps: step (1), firstly determining a regional power grid environment of a kind of current transformers under investigation, including an operation mode, and calculating the limit residual magnetism level and the limit transient current level of the current transformers under investigation on various installation locations; step (2), preparing test objects of large current steady state and transient state tests, and building an experimental loop; step (3), performing steady state and transient state large current test; step (4), processing waveforms of the large current steady state and transient state tests; step (5), fitting a hysteresis normalized curve; and step (6), optimizing five key parameters of a J-A model through the fitted hysteresis normalized curve, and acquiring a practical J-A model, that is an engineering model of a current transformer to be established. The method provided by the invention can establish the engineering model of the current transformer which can accurately reflect the transient and large current spread characteristics.