Passive daytime radiative cooling is a zero-carbon efficient cooling technology that reflects sunlight and radiates heat to the ultra-cold outer space without any energy consumption. While the existing radiative cooling materials are still difficult to achieve the efficient regulation of the broadband, which limits the further improvement of cooling capacity. Herein, a radiative cooling film is obtained by embedding rod-like dielectric particles (RLDP) with polyhedral and nanoporous structures into polymer. The polyhedral and nanoporous structure of RLDP yields a strong solar (0.25-2.5µm) reflectivity of 98.8%, and abundant optical phonon vibration peaks in the infrared band (6-20µm) emerges a high infrared emissivity of 96.0%, which result in a sub-ambient temperature drop of 5.3 °C under direct sunlight and 5.8°C at night. Moreover, the broadband high optical performance of RLDPbased film has a positive effect on maximizing the heat dissipation of objects (i.e. above-ambient cooling capacity) that generate tremendous heat and have a temperature higher than ambient. Compared with bare electronic equipment, RLDP-based film reveals remarkable above-ambient cooling performance and generates a temperature drop of 12.5 °C on the surface of heater. Given the efficient broadband optical property, eminent mechanical performance, self-cleaning property and the feasibility of large-scale preparation, RLDP-based film provides innovative strategy for thermal management in buildings, vehicles, and electronic equipment.