The invention discloses a pressure controlled automatic reversing working device for a punch of a rock drilling machine, which aims at realizing reliable reversing and fast resetting of the punch of the rock drilling machine. The pressure controlled automatic reversing working device comprises an impact mechanism 3, a master control two-position four-way hydraulic control reversing valve 9, a second two-position two-way hydraulic control reversing valve 13, a first two-position two-way hydraulic control reversing valve 14, a two-position two-way solenoid valve 7 used for resetting an impact piston D, a hydraulic control check valve 4, a check valve 8, a check valve 11, a throttling valve 6, a throttling valve 10, a throttling valve 12, a throttling valve 15, a reducing valve 5, a hydraulic pump 1 used for supplying pressure energy and an overflow valve 2 used for adjusting the system pressure, wherein the second two-position two-way hydraulic control reversing valve 13 and the first two-position two-way hydraulic control reversing valve 14 are used for controlling the two-position four-way hydraulic control reversing valve 9; and the second two-position two-way hydraulic control reversing valve 13 is used for return control of the impact piston in full-stroke movement, the first two-position two-way hydraulic control reversing valve 14 is used for return control of the impact piston in rebound movement, and the two two-position two-way hydraulic control reversing valves are respectively connected with an external control port K of the two-position four-way hydraulic control reversing valve and mainly play the role of relieving pressure, thus the flow rate is low, the mass of the valve plug is low, and fast reaction can be realized.