Abstract: Load test is a kind of regular tests of transformers. It’s also a basic test subject before transformer leaving factory, or undergoing transfer, heavy repair and fault. There are two main test contents, the load loss and short circuit impedance. These parameters are basic performance parameters of transformer, which identify the quality and performance of a transformer. In practical engineering, for miniature trial plant or low-capacity substation, if load test is carried out under rated current, the capacity of test energy source will be insufficient due to the bulk capacity of the underproof transformer. This may exceed the requests of associated experiment equipment, like voltage regulator, intermediate transformer etc. However, even the compensating capacitor is used to cut down the energy source’s capacity, the large volume and weight of compensating capacitor will result in certain difficulty. Aiming at the problems emerged in practical engineering through traditional testing way, article analyzes the principle of classical load test in theory, and puts forward a kind of improved experiment method. The article first proves the feasibility of improved method through computer simulation, then actualizes field load test to transformers through the improved experiment method and recalculates the load test parameters. Finally the article actualizes the error analysis and the cost comparative analysis between the improved method and the classical method. Results indicate that the improved method will decrease the limits to the intermediate equipment without increasing energy source capacity. So it is a good method to enhance the test operating efficiency and the economical benefit, which is able to meet the precision demands of practical engineering. So the improved method can become a kind of extension and development for the classical load test of transformer.