<p>For disclose the 3D spatiotemporal oscillation characteristics of nanofluid thermocapillary convection, this paper numerically studies the supercritical oscillatory process of nanofluids thermocapillary convection in a 3D rectangular cavity under microgravity conditions, and the propagation characteristics of flow field and temperature waves are analyzed. The results show that, under supercritical condition the flow field is composed of multiple dynamically migrating convective vortices, and the periodic temperature waves not only appear at free surface, but also inside the liquid layer. With increasing nanoparticle volume fraction, both the dominant frequency and amplitude of velocity oscillation exhibit linear reduction, while the oscillation period increases linearly. Furthermore, the propagation angle of hydrothermal waves increases progressively with nanoparticles volume fraction increasing, particularly, the angle from 27.5° increases to 33° as nanoparticles volume fraction varies from 0 to 0.05.</p>