Abstract: In order to improve the turbulence state of high-pressure water jet nozzle and to advance its cutting ability，flow conditioner was creatively proposed to improve the performance of jet.The flow conditioner with four kinds of profile types（cross，guide，square，flat) were designed and manufactured by adopting OMAX water cutting，which were respectively installed into the nozzle.Their performances were studied by experiments of flow coefficient，convergency and cutting.The function of the flow conditioner was discussed and the expression formula of cutting depth by water jet at fixed point was derived.Except for the lower flow coefficient，the performance of nozzle with a flow conditioner was evidently better than that without one，especially that its cutting ability have a greater improvement in the submerged area.For four kinds of flow conditioner，the cross type was the best，followed by guide，square，flat.

Key words: High-pressure water jet, Nozzle, Flow conditioner, Profile type, Cutting depth