I plan to visit China to attend the wedding ceremony of son with a Chinese national.

Hi Abdullah, do you hold an ordinary passport or an official passport at present? If you sitll hold an official passport, you don't need the entry permit for a stay less than 30 days in PRC. If you have an ordinary passport, then you need to apply for an S type I think. The documents include your passport, a photocopy of it, a completed application form attached with your recently-taken barehead photo, an invitation letter from your son if he's in PRC now, a copy of his passport and residence permit there, his birth certificate, and an invitation letter from duly authorized unit.