<p>Passive daytime radiative cooling (PDRC) exhibits efficient cooling performance to reduce global fossil energy consumption and has attracted enormous interest. An efficient PDRC technology for achieving daytime subambient cooling is supposed to exhibit ultra-high solar reflectivity and infrared emissivity within atmospheric windows, among which ultra-high solar reflectivity is the principal property. In most PDRC technologies, spherical particles are selected as scatterers to achieve high solar reflectivity because the Mie scattering effect of spherical scatterers can provide a high scattering efficiency. However, the weak backward scattering of spherical scatterers remains a drawback. In this study, several nonspherical scatterers with strong backward scattering are introduced and researched systematically. The numerical analysis results indicate that pyramidal scatterers provide the strongest backward scattering and square/circular scatterers exhibit the highest scattering efficiency. Besides, by considering scattering efficiency and asymmetry factor comprehensively, a dimensionless evaluation parameter is proposed, which can be employed as a quantitative design criterion to achieve the optimal-object-oriented designing of superior scatterers. This work can provide an innovative strategy for designing efficient passive daytime radiative cooling materials.</p>