The paper presents advances in investigations of a new jet , the self-resonating water jet, including its design principles, impacting properties of impact pressure and rock erosion, and field applications in China. The researches show that nozzles designed on basis of organ pipe structure can generate self-resonating cavitating water jets. As compared with conventional cone-shaped nozzle with 120 degree of taper angle, the amplitude of impulse pressure, and maximum impact pressure increases 24% and 37% respectively, and rock breaking efficiency increases by 1 to 2 times. Self-resonating water jets have been successfully applied in petroleum engineering. Roller bits, devices for treatment of near well- bore formation, self-excited oscillating water injectors with the self-resonating water jet technique have been developed, and great economic efficiency has been achieved.