Spaceborne multi-baseline interferometric synthetic aperture radar (InSAR) provides an effective solution for large-scale forest vertical structure inversion. The Hongtu-1 (HT-1) satellite, using a four-satellite cartwheel formation, enables single-pass multi-baseline acquisition and avoids temporal decorrelation. In this study, a complete interferometric processing workflow for HT-1 data is developed, including orbit correction, interferometric registration, phase correction, and tomographic calibration. Forest vertical structure is reconstructed using Capon-based tomography and compared with the single-baseline Phase Histogram (PH) technique. Experiments are conducted in Gabon using four HT-1 SAR images, with airborne LiDAR data for validation. The results show that both methods can retrieve forest vertical structure, while Capon provides more continuous profiles and higher accuracy. Capon achieves an RMSE of 5.43 m, outperforming the 6.49 m of PH. This confirms the feasibility of HT-1 for spaceborne tomography and its potential for forest vertical structure inversion, suggesting that such multi-baseline systems are worth promoting in future satellite missions.