The invention relates to a transformer core residual magnetism detection method based on a no-load current method. The transformer core residual magnetism detection method is used for on-site detection of large-scale power transformer core residual magnetism. The transformer core residual magnetism detection method comprises a current rising curve in a transformer no-load current boosting initial phase, a current declining curve in a transformer no-load current boosting initial phase, expression and calculation of a difference between the current rising curve and the current declining curve; and a transformer core residual magnetism determining standard. The core residual magnetism has a large influence on the transformer no-load current boosting initial phase, and the detection method is used to draw the current rising curve and the current declining curve by measuring the current value difference under the same voltage value in a voltage rising phase and a voltage declining phase caused by the core residual magnetism, and is used to determine the core residual magnetism by using the difference between the current rising curve and the current declining curve, and therefore the detection accuracy is high, sizes of required detection devices are small, weights are light, wire connection ways are simple, and the on-site detection of the transformer core residual magnetism is facilitated.