I think there are many reasons why China ranks high in the happiness index. In the past decades, China's economy has developed rapidly and people's living standards have been greatly improved. The government has also carried out many reforms in medical security, education and employment, which will have a positive impact on people's happiness. At the same time, China culture pays attention to the inheritance of values such as relationship and family, which is one of the important reasons for China's high happiness index.
Finally, it should be noted that the results of investigation and demonstration are often limited, and different data collection methods and sample selection will have an impact on the results, so it is necessary to understand and evaluate them as objectively and comprehensively as possible.