how can i get my china visa in hong kong in same day?

There are two options for you to get a new visa:
1. go to local exit-entry administrative department of public security bureau to apply for visa extension
or
2. go to Hong Kong or Macau to apply for a new visa. Even though you apply for rush service, it takes 2 working days (including the submission day. e.g. If visa application is submitted on the morning of Monday, collection time is on the morning of Tuesday; If visa application is submitted on the afternoon of Monday, collection time is on the afternoon of Tuesday)