APC evaluation theory (the achievement of Tsinghua University NGO Research Institute), the so-called APC theory refers to the sum of responsibility evaluation, performance evaluation and organizational ability evaluation. Accountability evaluation is "an institutional arrangement to ensure the credibility of non-governmental organizations, and its function is to help non-governmental organizations establish social reputation and brand"; The function of performance evaluation is to "improve the efficiency of the organization through evaluation and promote the improvement of the service quality of the organization"; The function of capacity assessment is to "promote the sustainable development of non-governmental organizations". The APC evaluation system transformed into practice requires professional teams to display their professional skills, grasp the foundation, grasp the norms and operate for a long time, which is actually the basic structure of an independent specialized agency.