Chinese stocks could attract more than $400 billion in inflows once shares are fully included in widely followed MSCI indexes, the world's largest asset manager BlackRock said on Wednesday.

The comment made by its managing director and head of China equities, Helen Zhu, was in response to the muted reaction from market watchers after MSCI decided last week to add 222 China A shares into its emerging markets index. Some even said that the move is not a "game changer on any front."

"A lot of these type of changes, you do have to implement them early on to provide the backdrop for the gradual changes and impact to come through. In terms of the MSCI inclusion, it is indeed only a first step, it's a relatively small step because the inclusion factor is only 5 percent at the moment," Zhu told CNBC at the sidelines of the World Economic Forum in Dalian, China.

"But over a medium and longer term perspective, this is very much just the first step in a very gradual and inevitable process of a full inclusion of China in the indices. When that full inclusion happens, China H plus A added together will be potentially over 40 percent of MSCI EM (emerging market), at which point we're talking about maybe $400 billion plus of potential inflows."