based on China's reality 不是修饰性状语，所以based与句子的主语并没有逻辑关系。这是评注性状语，是说话人对句子的解释，这个句子statement is based on China's reality. 即based 的逻辑主语是后面句子的内容。

We refrained from adopting a deluge of strong stimulus policies, and this was based on China's reality. 你现在可以清楚的看出，指示代词this指代的是前面整个分句。