"The national committee will travel to crash site on Thursday and then proceed to (the Ugandan capital) Kampala," Siraj Eddin Hamid told AFP.
Garang died on July 30 when a Ugandan presidential helicopter on which he was travelling crashed on its way back to south Sudan.
His death came just three weeks after he became first vice president under a landmark January peace deal he helped craft.
It raised fears about the peace process in the war-ravaged country and sparked deadly riots in Khartoum and southern towns, with some southerners charging the government might have had a hand in it.
Sudanese President Omar al-Beshir issued a decree on August 8 establishing the seven-member committee and named former vice president Abel Alier, a southerner who like Garang hails from the Dinka -- the region's biggest ethnic group -- to head the panel.
The committee also includes six aviation experts -- three from the Sudanese government and three from the former rebel group Garang headed, the Sudan People's Liberation Movement (SPLM).
In Kampala, the committee will meet with other teams involved in the probe, including the Ugandan side, Hamid said.
"There, we will coordinate with the other investigating teams," he said.
Sudan has said it will accept help from any country in its investigation and a few countries, including the United States, Britain and the United Nations have offered assistance. The Kenyans are also involved.
Hamid added that a four-man team, comprising two members from the Sudanese government and two from the SPLM, will head directly to Russia from Kampala with the Russian-built MI-172's black boxes.
"They will take the black boxes -- containing the aircraft's cockpit voice recorder and flight date recorder -- there for analysis," Hamid explained.
Ugandan President Yoweri Museveni has suggested that the crash, initially blamed on bad weather in a mountainous area of south Sudan, may not have been an accident.
The Sudanese national committee has a month to complete its investigation and present its findings to the president.