As China's economic development has shifted from quantitative growth to qualitative improvement, stakeholders have enforced stricter corporate social responsibility (CSR) requirements for listed companies. However, few studies have focused on companies and CSR in such developing economies. We used the CSR scoring system from Hexun Finance's website to group Chinese listed companies according to their CSR scores. By comparing the effects of merger and acquisition (M&A) announcements on different CSR scores, we found that, first, the average abnormal return (AAR) response time of the low-CSR acquirers group was eight trading days, much longer than that of the medium-CSR (three trading days) and the high-CSR group (four trading days). Second, from five trading days before, and 15 trading days after the announcement date, the cumulative AAR (CAAR) of the acquirers in the low-CSR group was 0.270, much higher than those in medium- and high-CSR groups. Third, after considering the CSR scores for the two years prior to the M&A and controlling for other factors affecting the M&A, the CSR performance of the above-mentioned M&As was still negatively correlated with the M&A announcement effect. This point to the need for further studying CSR and M&A announcement effects for Chinese companies.