Disclosed is a machine for grinding and polishing a safety valve flap by means of a magnetic fluid, comprising a first mounting mechanism (100) used for mounting a safety valve flap (105), and a second mounting mechanism (200) used for containing a magnetic fluid abrasive material (230), wherein the first mounting mechanism can drive the safety valve flap to enter the second mounting mechanism to come into contact with the magnetic fluid abrasive material and move relative to the magnetic fluid abrasive material to realize grinding and polishing of the safety valve flap; the second mounting mechanism further comprises a magnetic field generating device; and the magnetic field generating device agglomerates the magnetic fluid abrasive material, so that the safety valve flap is ground and polished by the magnetic fluid abrasive material in the agglomerated state. Also disclosed is a method for grinding and polishing by using the machine for grinding and polishing the safety valve flap by means of the magnetic f
