Mode　switching　is　an　important　process　in　unitized　regenerative　fuel　cells.　The　complex　interactions　of　heat　and　mass　transfer　during　the　operation　of　mode　switching　have　a　significant　effect　on　cell　performance.　Twelve　different　ways　of　mode　switching　were　proposed　by　controlling　inlet　boundary　conditions　of　supplies　and　operating　voltage.　Numerical　simulations　were　applied　to　analyze　the　dynamic　response　of　heat　and　mass　transfer　as　well　as　electrochemical　signals　under　the　different　ways　of　mode　switching.　Current　density　increased　with　mass　fraction　of　reactants.　Cell　heat　source　had　an　instant　response　to　current　density,　but　the　temperature　was　slow　to　respond　to　the　heat　source.　Hydrogen-side　inlet　velocity　had　minimal　impact　on　mode　switching.　The　time　for　cell　reaching　stability　increased　with　the　increase　of　voltage　change　time,　and　the　time　for　current　density,　mass　transfer,　and　temperature　reaching　stable　values　increased　in　order.　Unitized　regenerative　fuel　cell　had　similar　dynamic　response　in　the　2　period:　cell　temperature　increased　in　the　fuel　cell　mode　and　decreased　in　the　water　electrolysis　mode　after　mode　switching.