With the unique capability of tracking the dynamic evolution of electronic structure in the time domain, time- and angle-resolved photoemission spectroscopy (trARPES) has become a more and more important research technique in condensed matter physics. In this talk, I will introduce our recent work in correlated materials. In iron based compounds, we observe ultrafast coherent modulation of the electronic structure and possible metastable states. In the canonical charge density wave materials Rb_0.3MoO₃ , we observe ultrafast laser induced melting of the long-range order, which precedes the response of coherent nuclear atoms. We argue that the incoherent lattice phonons play decisive role in the melting of the charge-density wave in Rb_0.3MoO₃ , which should be generically considered in the study of laser induced phase transitions.