Phosphorescent organic light‐emitting diodes (PhOLEDs) with multiple functional layers are favorable for high device performance. However, due to the erosion between functional layers, it is still a great challenge to prepare multilayer devices with a low‐cost solution process. In this manuscript, 4,4′‐bis (4‐vinylphenyl) triphenylamine (VBTPA) can be in‐situ polymerized as the thermally crosslinkable hole transport layer and successfully applied to solution‐processed green light PhOLEDs by spin‐coating method. It had the styryl groups as the thermally crosslinking position and can be crosslinked at 175°C with short crosslinking time (20 min). The high thermal stability (446.0°C), good photoelectric property and excellent solvent resistance and so forth, made the crosslinked VBTPA achieve a good device performance in solution‐processed PhOLEDs. The turn‐on voltage was 6.1 V, the maximum luminance was 8271 cd m−2 and the maximum current efficiency was 12.4 cd A−1. It indicated that the hole transport material with styryl groups as the thermally crosslinking position can be crosslinked under lower temperature (<200°C) for shorter time and applied to the preparation of multilayer solution‐processed stacked PhOLEDs.