Abstract: This paper presents a new principle of piston pump, which possesses many advantages, such as "without leakage line", self-cooling, self-lubricating, multiway output, high pressure, high efficiency, long service life, light weight, simple structure easy to operate, saving energy and it could be used to make new pump with different performance and reform axial piston pumps widly being using now. It is proved through the test that the open channel piston pump is feasible in theory, reliable in operation and superior in performance.