A man was repeatedly assaulted in a Perth home by alleged kidnappers who then demanded money from his family, police say.

Three men have been charged with kidnapping and threats over the alleged incident in the northeast suburbs.

The 68-year-old had flown in from Melbourne with a 29-year-old man he met there over a business deal after arriving from China, WA Police alleges.

The younger man allegedly then took him to a home in Caversham where a third man was waiting, and he was held against his will and assaulted numerous times.

Police allege the man's family members were contacted with demands for money in exchange for his release.

The Caversham home was located by Financial Crimes Squad officers on Tuesday, who forced entry into the house.

The alleged victim was found inside with various injuries and taken to hospital.

The three men - aged 29, 31 and 37 - were all charged with kidnapping and demanding property with written threats.

The 31-year-old is due in Perth Magistrates Court on Saturday, while the 29-year-old is due in Midland Magistrates Court on May 12.

The 37-year-old will face Midland Magistrates Court on May 26.