The invention discloses an improved transformer substation grounding grid simulation test platform and a test method, wherein the test platform consists of an isolation transformer, a voltage regulator, an electrolytic tank and a protection resistor, and the power limit of the isolation transformer, the injected fault current and the resistance of a metal box used in the test are comprehensively considered in the selection of a protection resistor; the application method uses agar jelly to produce simulated block soil, and the agar jelly and a grounding grid model are integrally formed. The resistivity of the simulated block soil is changed, the size of the simulated block soil is trimmed, and the variable is controlled to perform soil resistivity type and soil range type related tests, and simultaneously, grounding grid improvement tests such as grounding grid material optimization, grounding grid overall design optimization and the like can also be performed. The improved transformersubstation grounding grid simulation test platform and the test method can improve the accuracy of the measurement result, provides a solution to the problem that the block soil test cannot be carried out, and can carry out test research on the simple block soil problem and the block soil problem under a double-layer soil structure.