"The second Il-76 transport plane departed at 18.45 Moscow time [14.45 GMT] for China," the official said. "Relief supplies include tents and blankets - what the victims of the earthquake need the most."
Another plane carrying 30 tons of Russian humanitarian aid, including tents, mattresses and blankets, landed in Chengdu earlier on Wednesday.
Monday's quake, which struck at 2.28 p.m. (06:28 GMT), was the worst to hit the country in more than three decades. According to official sources, the death toll from the quake, measuring 7.8 on the Richter scale, has reached 14,866. The epicenter of the earthquake was 57 miles (92 km) northwest of Sichuan's provincial capital, Chengdu.
An estimated 100,000 Chinese troops are involved in the ongoing relief operation. The government has allocated a total of $125 million in emergency aid for the quake-hit areas, while Chinese citizens have donated over $120 million in the past two days to help the victims of the disaster.
The Russian Ministry for Emergency Situations earlier said Russia was ready to send additional aircraft with humanitarian aid, a rescue team and a mobile hospital to China to assist in the relief operation if a request was made by the Chinese authorities.