You can buy a house only after applying for a residence permit in Kunshan for more than 5 years

Yes.

According to the Kunshan Civil Affairs Network, you must have a tax payment certificate in Kunshan for five consecutive years or a social insurance certificate in Kunshan for five consecutive years. You must also have a legal and valid temporary residence permit for five years. In addition, if you are outside Kunshan I have bought a house with a local loan in Kunshan. If I want to take a loan to buy a house in Kunshan, the down payment ratio needs to be more than 60%.

Residence permit is an attempt by some developed cities in China to learn from the "green card" system of developed countries, to formulate skilled immigration methods for China, and ultimately to accumulate experience in forming China's national "green card" system.