Rapid urbanization in China has been a double-edged sword, spurring cultural prosperity while contributing to cultural resources depletion. This study investigates a critical yet underexplored issue: How has the diversity and abundance of cultural resources evolved in Chinese megacities during the urbanization process? While scholars have increasingly focused on the role of cultural resources in sustainable urban development, yet issues related to the evolution of these resources have not been adequately explored. This study fills this gap by innovatively applying a modified species diversity and abundance index to quantifies the diversity and abundance of cultural resources, and then we detect the evolution pattern in types and absolute quantities of urban cultural resources across 14 major Chinese cities from 1999 to 2018. Findings reveal that the rapid growth of these megacities positively impacted the diversity and abundance of cultural resources. However, significant potential remains for achieving a better balance between the two dimensions and for promoting a more balanced geographical distribution. The research provides valuable insights for central and local governments to develop policies that enhance cultural resources diversity and abundance, contributing to more sustainable urban development.