Abstract: To explore how to improve the performance of scramjet engines operating at a flight Mach number around 10, we proposed a method to achieve combustion enhancement by means of the cavity-aft-shock, and designed the three-dimensional scramjet article with a both-side-symmetrically-configured cavity combustion chamber. Using a combination of the excited OH^* chemiluminescence visualization and wall pressure measurement, burning characteristics of the hydrogen jet injected upstream of the cavity in a highly supersonic crossflow of the scramjet combustor were experimentally studied at the nominal condition of Ma = 10 in a free-piston driven high enthalpy shock tunnel. The repeatability of the simulated flow field was discussed, and the evolution characteristics of hydrogen combustion, flame-stabilization structure, and heat release profiles were given. Across all experimental cases, the stagnation parameters of the freestream flow remained constant with low standard deviation, allowing for effective analysis of hydrogen combustion characteristics. The evolving features of OH^* chemiluminescence indicate that the so-called "shock tube flow-combustion" in the engine article is formed at the initial stage of the crossflow establishment due to the employment of the fuel injection before the arrival of the highly supersonic crossflow, leading to the autoignition at the contact interface of the high temperature crossflow with the injected hydrogen, while the flame ultimately anchors at the jet wake of the bodyside wall and the whole flow path around the cavity aft due to the coupling interaction of the autoignition in high total temperature crossflow and cavity-aft X-type shock pattern. The OH^* luminosity and wall pressure distribution features within the effective test time demonstrate that the combustion enhancement is associated with the cavity-aft X-type shock patterns, which generate the drastic heat release-induced pressure rise. The results are useful to promote combustion efficiency of high Mach number scramjet engines by means of cavity configuration presented in this paper.