The relationship between public attitudes toward animals and human demographics has been well documented during the last few decades, but the influence of human ethical ideologies on public attitudes toward animals and animal welfare has been rarely investigated, especially in developing countries, such as China. The present study introduced two scales (Animal Issue Scale [AIS] and Animal Attitude Scale [AAS]) to investigate the Chinese people's attitudes toward animals and the manner in which their outlook related to ethical ideologies (idealism and relativism), which classified people into four ethical positions: situationists, subjectivists, absolutists and exceptionists. Moreover, it also showed how ethical ideologies and their interaction with human demographics influence respondents’ attitudes toward animals. The results of an online questionnaire (n = 504) distributed throughout China suggest that compared with middle-aged and old respondents, the young demonstrated significantly more positive attitudes toward animals. Absolutists showed the most positive attitudes toward animals, while subjectivists showed the least. People's attitudes toward animals were positively affected by idealism, which confirms previous findings in developed countries. However, people's attitudes toward animals were negatively affected by relativism, which is inconsistent with findings in developed countries, showing that ethical relativism failed to influence attitudes toward animals. Our results indicate that the same mechanisms underlying the effect of ethical idealism on attitudes toward animals might work in different countries to increase awareness on animal welfare. However, the manner in which ethical relativism influences attitudes toward animals may differ between developed and developing countries.