Optical methods research of high speed water jets issuing from the nozzle which creates high pressure stream results are presented in the current paper. Current work aims to investigate new knowledge about two-phase liquid flow under extreme conditions, and the analyze possibility of device design optimization. The process of high-speed water jet outflow from the focusing tube of the Flow WaterJet Mach3 hydroabrasive cutting machine, its development process and the stationary flow state overall time period near 1 second is considered in the current paper. Shadow method was used to investigate an initial stage of high-speed water jet outflow from the focusing tube as well as jet a head part movement dynamic for 0.2-0.4 milliseconds period with a working pressure 400MPa. In order to study jet formation process high-speed camera Photron FASTCAM SA5 with framing rate no more then 100.000 frames per second and with exposure time 1μs was used. Videodata and pictures have been processed. High-speed water jet outflow spatial-temporal characteristics have been measured as well as the stationary mode establishment process. As a result of image series digital processing jet velocity and jet head part acceleration at the initial stage are measured.