The invention belongs to the field of high-temperature high-speed fluid flow researches and particularly relates to a high-temperature high-speed jet reflection velocity field test method. The method is characterized by including firstly, processing an H-shaped test rake, secondly, preparing test equipment, thirdly, starting test after synchronizing a system clock with a jet generator, fourthly, processing data, and fifthly performing analysis and computation. The method has the advantages that the number of measuring points, test data volume and test start-up times are reduced to a bearable range of an external field; the ground of the external field is undestroyed while steadiness of the test rake is guaranteed, and the problem about influence on a plastic piezometric tube due to condensation and high temperature of the external field is solved; a multi-channel acquisition delay unloading method is adopted for massive real-time high-frequency dynamic sampling data, the problem of lack of bandwidth and rate of a data acquisition and storage system is solved, meanwhile data accuracy is improved, start-up times of a jet device are reduced, and test cost is saved; the problem about one-to-one correspondence of the test data and jet states is solved; and a set of data acquisition, processing and analysis method is established.