Abstract: Before the commissioning of a newly built or reconstructed 110kV transformer, an upflow test should be conducted to comprehensively verify the correctness of the turns ratio, polarity, winding arrangement, and internal secondary lead-out wires of the current transformers on all sides. This ensures the reliability of the relay protection system and avoids unexpected operation or failure to operate of the main transformer protection due to incorrect polarity of the current transformers, both during phasor testing and actual operation. This article starts by introducing the equivalent circuit and parameter calculation of the transformer, and then presents a matrix-based approach for conducting the upflow test on a 110kV transformer, using the data from the main transformer nameplate. Subsequently, the feasibility of the proposed test scheme is validated by comparing the theoretical values with the actual test results of a practical transformer substation. This verification ensures the correctness of the test scheme proposed in this article.