The majority are based in the capital, Kinshasa, but about 900 live elsewhere, making evacuation plans harder to draw up.
Two military teams are being sent to the region, said Belgian Prime Minister Guy Verhofstadt.
They will prepare the ground for the possible evacuation of up to 2,500 Belgian citizens who still live or work in the former colony.
The majority are based in the capital, Kinshasa, but about 900 live elsewhere, making evacuation plans harder to draw up.
"This is very much planning, and nothing like a decision to evacuate," Belgian Foreign Ministry spokesman Michel Malherbe told BBC News Online.
"The situation is calm at the moment, and there is no reason to evacuate."
Troops
Mr Malherbe said it was too soon to say whether the evacuation plan, if brought into effect, would be used to bring other westerners out of DR Congo.
The first team was due to leave Belgium for DR Congo later on Wednesday. The second will take the same route on Thursday.
Mr Verhofstadt told reporters that one team would comprise security officers, and the second would be made up of troops who would carry out the evacuation, if it went ahead.
Belgium was the first country to say it had confirmation of the death of President Kabila.
It said the information had come from reliable sources, and on Wednesday said it was standing by its announcement, while admitting the exact details were still very unclear.
"It seems there is still confusion at the level of information about who was responsible (for killing Kabila). A general or a bodyguard, that is not yet sure," Foreign Minister Louis Michel told Belgium's RTBF radio on Wednesday.
"Today we cannot confirm that it was a coup d'etat - we don't know what it was," he added.
The confusion over President Kabila's fate deepened on Wednesday, when reports said he was alive but seriously injured. Later news reports said he had died of his wounds while being taken to Zimbabwe.