"China is going through an economic transformation period from 2011 to 2015, with the pace of growth adjusting from high-speed to medium-to-high-speed. However, with a series of important reform measures adopted by the government, such as expanding free trade zones and the ‘One Belt and One Road' initiative, the economy this year is likely to run smoothly," said Chen Xikang, an operational research expert who took part in writing the forecast.

The "One Belt and One Road" plan, refers to the Silk Road Economic Belt and the Maritime Silk Road of the 21st Century, was an initiative put forward by President Xi Jinping in 2013 to promote trade and communications in the region.

In 2014, bilateral trade volume between China and countries in the region enjoyed a 7 percent yearly increase.

"The economic growth rate is unlikely to drop below 6 percent in the coming one and a half decades," Chen said.

Chen predicts that the average annual GDP growth rate will hover between 6 percent to 8 percent till the year 2030, and then further decrease to 4 percent to 6 percent over the next 20 years, if not influenced by profound changes in external demand or government intervention.

Zhu Baoliang, director and chief economist of the Economic Forecast Department under the State Information Center, another forecasting research institute, is less optimistic for the year 2015.

"Although I basically agree with the forecasting logic of the Chinese Academy of Sciences, my research results show that this year's GDP growth rate is at best 7 percent," he said.

"China's excess capacity problem could not just be cyclical. Instead, it is a structural problem. The growth rate will see no improvement until most existing capacity is put to productive use," he said.

Niu Wenyuan, an expert on sustainable development as well as a consultant for the State Council, said that the focus of government should change from GDP growth rate to the quality of GDP.

"The GDP growth rate is going down as China readjusts economic structure, but we can hedge the declining pressure by increasing the quality of GDP," Niu said. "If the growth implies more responsibilities in redistribution and social assistances, it will help us avoid the middle-income trap."

Niu and his team developed a system to evaluate China's GDP quality from its contribution to economic efficiency, social benefit, environment protection, improvement on people's livelihood and sustainability of public management.

The quality report was published on Wednesday in Beijing, which showed that China's GDP quality had increased by 46.5 percent from 1993 to 2013.

"The GDP quality of China had seen a faster increase since 2013, and I am expecting it to increase by 24.2 percent to 33.8 percent till the year 2020," Niu said.