As one of the hot spots in current political science research, political polarization has become an indispensable perspective to peer into the predicament of western democracies, Qi Lingling remarked in Open Times, No. 3, 2022. The driving factors behind political polarization include social and economic inequality, demographic structure change, ethnic and cultural conflicts, media influence and other structural changes that bring ideological differentiation and party identification. It is subject to the design of a country's electoral system. Relevant conclusions, however, are not yet clear in Western countries except the United States. Political polarization can result in more explicit political stance of strong political parties and political elite, motivating democratic participation with more powerful opposition parties formed so that democracy works better; it can also shatter democratic consensus among multiple forces, destroy political compromise, cause political gridlock with government efficiency reduced, and even lead to democratic backsliding and collapse. However, it remains unknown what conditions can stimulate positive effects of political polarization on democracy and curb its negative effects.