An investigation team sent by the State Council, or cabinet, will give details of the search and rescue effort and the hunt for the black boxes at a news conference on Tuesday evening, state television said.
The last commercial jetliner to crash in China was in 2010, when an Embraer E-190 regional jet flown by Henan Airlines went down, killing 44 of the 96 aboard.
Highlighting the top-level concern, Vice Premier Liu He went to Guangxi on Monday night to oversee search and rescue operations.
The disaster comes as planemaker Boeing seeks to rebound from several crises, notably the impact of the coronavirus pandemic on air travel and safety concerns over its 737 MAX model following two deadly crashes.
Once it is found, the cockpit voice recorder could yield clues to what went wrong with Monday's flight.
"Accidents that start at cruise altitude are usually caused by weather, deliberate sabotage, or pilot error," Dan Elwell, a former head of US regulator the Federal Aviation Administration, told Reuters.
Elwell, who led the FAA during the 737-MAX crisis, said mechanical failures in modern commercial jets were rare at cruise altitude.
The US National Transportation Safety Board (NTSB) on Monday appointed an investigator, as the Boeing aircraft was produced in the United States, but it was unclear if the investigator would travel to China.
On Monday, China Eastern and two subsidiaries grounded its fleet of 737-800 planes. The group has 225 of the aircraft, data from British aviation consultancy IBA shows.
As of Tuesday, other Chinese airlines had yet to cancel any flights that use 737-800 aircraft, according to data from Chinese aviation data provider Flight Master.
Among the passengers on flight MU5735 was the chief financial officer of Dinglong Culture, a Guangzhou-headquartered firm whose businesses range from entertainment to titanium mining.
A provincial daily cited a woman as saying six of her family members and friends were on the flight to Guangzhou, where they had been due to attend a funeral.
Onshore-listed shares of China Eastern slumped over 6.5 percent on Tuesday, while those trading in Hong Kong fell nearly 6 percent.
