The invention discloses an 
oxygen-injection double-
stroke internal combustion engine and a running method thereof. The 
oxygen-injection double-
stroke internal combustion engine comprises a high-pressure 
oxygen pipe and a pressure stabilizing device; a high-pressure 
nozzle, a 
spark plug, an oil 
injector and an 
exhaust valve are fixed to the top end of the cylinder; the high-pressure oxygen 
pipe isconnected with the high-pressure 
nozzle; a pipeline where the high-pressure oxygen 
pipe is connected with the high-pressure 
nozzle is provided with the pressure stabilizing device; when the rotation angle of a 
crank is changed from 230 degrees to 360 degrees, a 
piston is sequentially subjected to compression, oil injection and 
spark plug ignition processes; and when the rotation angle of the crankis changed from 0 to 230 degrees, the 
piston sequentially does work and executes an exhausting process. According to the oxygen-injection double-
stroke internal combustion engine disclosed by the invention, an existing four-stroke internal 
combustion engine is changed into a double-stroke internal 
combustion engine, a gas feed stroke is canceled, a compression stroke and an exhaust stroke of theoriginal four-stroke internal 
combustion engine are integrated as one stroke, thus 
zero emission of 
NOx is realized, and the emission load of HC is remarkably reduced.