This paper places foci on two points: The one is that what kinds of efforts ASEAN has been made?;The second is how big is China's contribution to diminish developmental divide in ASEAN? The necessary and sufficient condition of regional integration is the confidence and identity in the region. We argue that diminishing developmental divide is crucial to strengthen the identity among related nations. ASEAN has been steering IAI for 12 years opportunely. IAI is the main project in which almost all of the east asian countries are taking part. China has been enlarging and intensifying politico-economic influences on the South Asia regardless of ever-increasing 'China threat' notion in neighbor nations. However, the China's concerns of ASEAN is sufficient to raise doubts of purity in that she is indifferent to the ASEAN's common interests especially in resolving developmental divide. The amount of China's contribution in IAI fund is trivial, smaller than India or Pakistan. Besides, China is interested in the projects directly and indirectly related to the national interest instead of contributing to reduce developmental divide of ASEAN.