A first-order structural phase transition is typically a displacive or reconstructive transformation. The latter has been considered as a non-direct group-subgroup symmetry transition. However, with an alternative pathway, recent symmetry group theory predicts such a reconstructive transition can be realized via a multi-step displacive mode. So far, no direct observations of such a displacive transition pathway under pressure have been reported due to lack of sufficient temporal resolution. Here, we present our experimental results on the phase transition of tin with a novelly designed ultra-fast time-resolved x-ray diffraction (tens of microseconds) combined with a series of rapid compression (up to 51.5 TPa/s), revealing the missing region in both time domain and compression rate between static and shock compression. The pressure-induced first-order phase transition from -Sn(I41/amd) to -Sn(I4/mmm) without direct symmetry operation shows distinct displacive characteristics in the sequential x-ray diffraction measurements, and the transition time is observed to depend on the compression rate. The deficit of summed phase fraction of -Sn and -Sn from unity directly derived from diffraction peak intensity during the phase transition time shows a clear compression rate dependent profile, which refers to the existing of intermediate phase. Solid-state Nudged Elastic Band calculations confirm the collective displacive paths of all atoms during the transition, and the corresponding XRD simulation patterns show consistent results to experimental time-resolved XRD observations. This dynamic structural evolution occurs on the microsecond time scale, which is orders of magnitude shorter than conventional high-pressure XRD experiments. Our results shed new light on the dynamics of the traditionally assumed reconstruction phase transition on microsecond timescale.