Wen arrived at the disaster zone early Saturday and urged local officials to make contact with every village in the region before the end of the day.
At least 80 people were killed in the quakes, two of which had magnitudes of 5.7 and 5.6. More than 700 people were injured and an estimated 200,000 people fled their homes.
Rain was forecast in the area, raising the risk of landslides.
Wen spent the predawn hours visiting hospitals and shelters and speaking with soldiers and other relief workers taking part in the rescues, China's official Xinhua news agency said. He warned everyone to be on guard for further tremors.
"The quakes are not over yet," Wen said. "Aftershocks continue, and within a period of time we will need to guard against secondary and geological hazards."