The fact that Donald Trump finally won the US Election 2016 provoked criticism on Lsocial media，big data analysis seems to show great advantages in internet opinion research. Does this mean that methods of random sampling and the like used in public opinion research is outdated？Based on a comparative analysis between traditional methods and big data analysis in the case of US Election 2016，this paper argues that，when doing analysis on social opinion，on the one hand，we should apply big data analysis in order to understand the social ethos revealed in cyberspace；while on the other hand we should not overlook the value of traditional methods of public opinion research in order to make of for what has missed in internet opinion.