How can I get working visa free

You want to apply for a work visa of Mainland China in HK? Then you need apply at the visa center in HK. And you may need a Foreigners Employment Permit of China, as well as Invitation Letter or Confirmation Letter of Invitation issued by relevant Chinese entities. And you need to pay the regular visa fee and service fee of the visa center. Also, you'd better know that the success rate is quite low if you apply from a third region other than your home country.