24 Hours Permit - Indonesian

Calvin, your question is not clear because your are mentioning a "return to Jakarta". Does that implies that your flight itinerary will be:

Indonesia - Beijing - Indonesia

If this is the case, you are not eligible for any kind of visa free transit options because this is not a transit and you need to obtain a Chinese tourist (L) visa because this is just a round trip.

In opposite case, if you are arriving from a third country to Beijing and proceed after 20 hours of layover to Jakarta, fore example:

Seoul - Beijing - Jakarta

You will be eligible for 24 hour visa free transit and you don't need any kind of visa.

So, if my route : seoul - beijing - jakarta, i can use 24h free visa transit, but can not leave the airport?
Because i will wait from 19.20 until 14.30 next day.

You are partly right. You will definitely be covered by 24 hour visa free transit, but to be allowed to exit the airport you will need to apply for a temporary entry permit at 24 hour visa free transit counter upon your landing in Beijing. Since your layover is very long and during the night hours, you are advised to book your accommodation in advance and to have a printout of your accommodation booking confirmation. Basically, this is your best chance to be granted a temporary entry permit or in other words to be allowed to exit the airport.