Visa Free entry for 10 days

Yes, this is all possible and you are correct in your assumptions. Also, the time spent in Hong Kong does not count against those 10 days because Hong Kong has separate immigration policy.

There are two main details to highlight regarding your travel plan:

1. You can really enter mainland China from Hong Kong, but this has to be done by ferry from Hong Kong to Shekou port in Shenzhen or to Nansha port located south from Guangzhou. These are two eligible options to start enjoying your 10 days visa free transit stay in mainland China. It is highly advisable to arrive in Shekou or Nansha until 15:00 because the first shift of the employees are by definition always better versed as far as this rule is concerned.

2. Even before your departure from Hong Kong toward mainland China you will have to buy your flight ticket from Beijing to Thailand and please, remember, your flight cannot transit in Hong Kong. It has to be a flight of nonstop type Beijing - Thailand. In other words, your visit to mainland China has to have its immediate points before and after in two different countries or eligible territories (eligible territories are Hong Kong, Taiwan and Macau). In other words, an itinerary

Hong Kong - mainland China - Thailand

is eligible, but an itinerary

Hong Kong - mainland China - Hong Kong - Thailand

is not.

Now, when you are informed, you can proceed with your travel plans with absolute peace of mind.

Thank you very much. This was very informative. I have a question about the itinerary. Is it not possible to visit Shenzhen or Guangzhou for a day of exploration? For example, on day 1, I go from hong kong - guanzhou, explore the city for the day, and then go back to hong kong where my hotel is? and then day 2, I go from hong kong to shenzhen, explore for only the day and then go back to hong kong ?

Could you go from Macao to Shenzhen (Shekou) and then from Shenzhen back to Hong Kong? Would that count?

Jay, no, you cannot have an itinerary like:

Hong Kong - mainland China - Hong Kong

This is round trip and not a transit. The immediate points before and after your mainland China visit have to be in two different countries or eligible territories. Eligible territories are Hong Kong, Taiwan and Macau.

As you can see, in order to enjoy 240 hour visa free transit, you need an itinerary of this kind, for example:

Hong Kong to Shekou (Shenzhen) or to Nansha (south from Guangzhou) strictly by ferry and after more than 24 hours to Macau, again strictly by ferry. Even before your departure from Hong Kong you will have to have a ferry ticket from Shekou to Macau in your hands as a proof that you will be really in a transit. This is the way how you can use 240 hour visa free transit.

If you want, you can visit Shenzhen on a day visit, but in that case you will have to rely on Shenzhen 5 days visa on arrival that you will have to obtain at the border crossing in the morning hours. This visa limits you to Shenzhen city limits only. If you ask me, the option Hong Kong - mainland China - Macau is by far better. It will be your choice to decide.

T, you can definitely use an itinerary:

Macau - Shekou - Hong Kong

By ferry from Macau to Shekou, but from Shenzhen you can take a train to Hong Kong. However, you have to stay in China for more than 24 hours to be eligible for 240 hour visa free transit. When planning this scheme, you have to know that you will have to buy a train ticket from Shenzhen to Hong Kong even before your departure from Macau. Also, you will have to take exactly that train you have bought your ticket for.

Thanks for that info.
I plan to go to shenzhen, then guangzhou, then i will take the night train to beijing. You mentioned that I already have to have a plane ticket to leave beijing to another country. If i have a ticket for 31 December, can i leave earlier on the 30th if i decide to leave a day early? Or do i have to leave on the ticket i showed as proof of transit?

Departing earlier is possible and allowed in general as long as your immediate point after mainland China is different than the country (or eligible territory) you have used to enter mainland China. As said, it is possible, but generally not recommended to use other tickets beside the one you have used to enter the country. It is the question of your reliability in the eyes of the Chinese immigration authorities.