Approximately 80 percent of all flowering plants require animals as pollinators. In this study, we systematically examined the structure and types of flowers, pollination process, media and methods, dependence of crops on insect pollination, concept of insect pollination function and service, and evaluation methods of insect pollination function and service value. The quantity of pollination function and the value of pollination service by insects in the agricultural ecosystem were evaluated. The results showed that food crops, fruits, vegetables, and commercial crops depend on insect pollination to some extent. Based on insect pollination dependence, crop yields, and crop prices in 2015, we found that quantity of pollination function for 22 types of major crops in China was 180 million tons. The value of pollination services was 886.05 billion RMB. The value of insect pollination services to major crops accounted for 1.3% of the GDP in 2015, which is of great economic value. At the provincial level, the quantity of pollination function and the value of pollination service for major cultivated crops in 2015 were ranked among the top five in Shandong, Henan, Hebei, Shaanxi, and Xinjiang, with the annual pollination service value exceeding 50 billion RMB. These results indicate that the main crops in these five provinces are highly dependent on insect pollination. Evaluating the pollination function is important for understanding the biological and ecological effects of insects on the biomass or yield of crops. Studies of the value of insect pollination service can reveal the economic effect or economic value of insect pollination. And it also help and support the decision maker or manager in determining whether to invest in the corresponding manpower, material resources, and financial resources to maintain or enhance the diversity and population quantity of pollinated insects for cultivated crops.