The conventional high-velocity oxy-fuel (HVOF) process has characteristics of high flame velocity and moderate temperature, and is widely used to deposit cements, metals and alloys coatings such as WC-Co, nickel and stainless steel. In this paper, a high pressure HVOF system with combustion chamber pressure up to 3.0MPa, and with characteristics of higher flame velocity and lower temperature was developed. In-flight particle velocity was measured using the DPV-2000 system at combustion chamber pressures from 1.0 to 3.0MPa, and stainless steel 316L powder was deposited at a combustion chamber pressure of 3.0MPa. The influence of spray conditions on the coating microstructure, deposition efficiency and micro-hardness were investigated. It was shown that the combustion chamber pressure has significant influence on particle velocity. Dense coatings composed of unmolten or partially molten particles could be deposited by varying the spray parameters. In the experiment, deposition efficiency up to 90% was achieved at the optimized spray conditions.