Titanium (Ti) alloys are mainly used in medical implants and aerospace applications where high fatigue strength is significant. Most of the titanium based components are subjected to unconventional machining to get the final shape of the product. Because, Ti based alloys are very challenging to machine usingconventional processes. In this work, the unconventional technique of abrasive water jet machining (AWJM) was carried out on Ti6Al4V under variation of the machining parameters such as water jet pressure (WJP), abrasive flow rate (AFR) and standoff distance (SOD). The surface integrities such as roughness, microstructural characterization and residual stress were investigated on the machined surface of Ti6Al4V. The orientation dependence of the compressive deformation in the polycrystalline Ti6Al4V alloy was investigated on the basal(0001)α, prismatic (1010)α and pyramidal (2110)α planes. The AWJM has induced the mechanochemical oxidation on the machined surface of Ti6Al4V alloy. The grain boundary network is the complex structure in the polycrystalline material; though, an attempt has been made in the present study to analyze the induced grain boundary, phase (α/β) fraction, dislocation, and oxide formation during the AWJM. The experimental results exhibited that the grain boundary dislocation density and average misorientation angle were increased and thegrain size was reduced with increasing the water jet pressure (WJP). Moreover, the compressive deformation was induced the residual stress on the machined region of Ti6Al4V. The β-phase of the Ti alloy has been transformed to α-phase when WJP was increased together with the oxygen content.