Maduro provided no specific details, but said Wednesday scientists determined the process could be "quite difficult."
"The decision should have been taken much earlier," he said.
"More than your physical body, we have the commander in eternal memory, especially this generation who heard it, touched it, saw him," Maduro told the audience at the Book Fair of Venezuela. "We have to keep alive his image, his voice, his thinking."
Chavez, 58, died earlier this month from cancer and officials had planned to have his body eternally on display like that of former revolutionary leader Vladimir Lenin of Russia, CNN reported Thursday.
Meanwhile, Maduro filed papers Monday to officially register to run for president. Elections to replace Chavez are scheduled for April 14.
Opposition candidate Henrique Capriles Radonski, 40, ran against Chavez last year and lost, but said he's ready for a fight this year, CNN reported.
"My fight is not to be president. My fight is for Venezuela to move forward," he said.