The 44-year-old probationary constable's home, in the New South Wales central west town of Cowra, was raided by police today after a tip off provided to Interpol by their Croatian counterparts.
Croatian police were investigating pornography downloaded from a website hosted in that country, NSW Police said.
Police raided the policeman's home at 8.15am (AEST), seizing a computer hard drive and a replica pistol.
Child pornography was allegedly found on the computer, police said.
The officer has been charged with possessing child pornography and a prohibited weapon.
He will appear in Cowra Local Court in November.