The latest blast took place at an apartment block at 08:00 local time (00:00 GMT) in Liucheng county, said state media.
Seventeen separate parcel explosions hit Liucheng on Wednesday.
A man suspected of having built the bombs - 33-year-old Wei Yinyong - died in one of the blasts, media said.
Earlier reports said a suspect had been arrested.
The cause for Thursday's blast was not clear, and no casualties have been reported. It is also not known if the blast is connected to the multiple explosions on Wednesday.
Thursday's explosion took place at a six-storey building in a residential area. Xinhua news agency said the force of the blast had caused debris to rain down on a road opposite the building.
Local police issued a statement calling on the public to be wary of accepting parcels sent by strangers or packages "sent by non-proper channels".
The local postal service has halted all deliveries until Saturday.
The parcel bombs on Wednesday targeted a prison, a railway station, a hospital and a shopping centre among other locations.
State media said 51 people were injured in the afternoon's blasts.
A video reportedly of one of Wednesday's blasts taken from a street surveillance camera has since emerged, showing a person being catapulted out of a shop as a bomb goes off inside. Another person walking down the street past the shop is knocked to the ground by the powerful blast.
The BBC's John Sudworth in Beijing says there have been a number of cases in China of disaffected people with a legal grievance against the authorities using explosive devices in public attacks.
Chinese authorities are investigating a fresh explosion in Guangxi province, following a series of parcel bombs that have left 10 people dead.