This study is the first to report the tests of a parallel-staged TSTO model with dynamic longitudinal stage separation (LSS) at different AoA values in the JF-12 hypersonic flight duplicated shock tunnel. The high-speed PED is developed for the dynamic test technique in shock tunnel. Static tests show the good aerodynamic performance of the TSTO model. Dynamic tests show that the small stage gap of LSS leads to weak type I and VI SSI, with short-time weak shock reflection and weak oblique SBLI in the flowfield at high AoA values. Furthermore, no shock reflection or weak oblique SBLI is observed in LSS at small AoA values, so the aerodynamic interference of LSS is weak. In addition, although the orbiter exhibits a smooth separation maneuver in both LSS tests, it tends to fly in a nose-up attitude at AoA = 8.3 deg and a nose-down flight attitude at AoA = 4.5 deg. Hence, the most appropriate AoA condition for the LSS of the TSTO model may be expected in the middle of 4.5 and 8.3 deg. No stage recontact is observed during LSS, and the safety and feasibility of LSS for the parallel-staged TSTO model are demonstrated experimentally, which is important for the success of the future TSTO system.