Disclosed are a header assembly and a heat exchanger. The header assembly includes: a header; a distribution member disposed in the header and having a distribution opening; a regulating member disposed movably at the distribution member and configured to regulate the distribution opening; and a driving member configured to magnetically drive the regulating member to move so as to regulate the distribution opening. By means of changing the position of the driving member, the header assembly and the heat exchanger are capable of changing the position of the regulating member via magnetic force, thereby regulating the distribution opening. Therefore, requirements under different operating conditions can be satisfied, and the applicability and distributing effect for refrigerant are improved.