Thermal comfort is essential for regulating the body's metabolic rate and organ function. Passive radiative cooling (PRC) allows for spontaneous cooling in direct sunlight without external energy input. However, this single-function cooling cannot adapt to highly dynamic weather and even leads to overcooling. Therefore, dual-mode structures that include radiative cooling and solar heating are becoming increasingly attractive. Herein, we fabricate self-assembled Janus film with reversible solar heating and radiative cooling properties, capable of harvesting energy from the sun and outer cold space without energy consumption. In cooling mode, porous PVDF-HFP film prepared through a simple phase-inversion procedure exhibit high solar reflectance and mid-infrared emittance, conducive to radiative cooling. When switching to heating mode, the Ti₃C₂T_x MXene film fabricated by minimally intensive layer delamination (MILD) method and vacuum filtration has selective solar absorption ability, which could maximize solar energy absorption and reduce radiative heat loss. The outdoor experiment shows that its cooling/heating mode can achieve the temperature drop/rise of 6.2°C/17.3°C compared to ambient temperature, respectively. In addition, MXene layer features higher thermal conductivity than PVDF-HFP, which allows local heat to be rapidly spread out and dissipated through the radiative cooling layer. This dual-mode design may open the pathway for developing switchable radiative cooling and solar heating systems for multifunctional thermal management.