In this talk, I will report recent progress on the modeling of collective behaviors appearing in biological and social complex systems, in particular flocking and synchro-nization. Flocking and synchronization of self-propelled particles are ubiquitous in our biological systems, for example, flocking of birds, swarming of fish and synchroniza-tion of neurons, etc. I will discuss how these macroscopic collective behaviors can be emerged from the simple interaction rules at the microscopic level, and present re-cent mathematical development on the aforementioned collective behaviors via several mathematical models.