In this paper, an experimental evaluation of the surface microstructural integrity of Si3N4 ceramics milled with abrasive waterjet was studied. The results show that the surface residual stress resulting from abrasive waterjet milling process for ceramics is compressive, and the compressive residual stress ranges from negative 203MPa to negative 19.6MPa. The results also show that the water pressure, the standoff distance, nozzle traverse speed and the lateral spacing have strong effects on the surface residual stress. The results also show that there is some enhancement in the hardness of AWJ milling surface, and it is affected by milling process parameters. The micro-topography of the milled surface cross section shows that there is a thin deteriorative layer in milled layer, in which no obvious crack is observed. Since the surface residual stress is compressive and the surface hardness increases, the milled surface deteriorative layer by AWJ could improve the surface quality.