In order to solve the problem for high initial frequency of unilateral lightweight phononic crystals, a phononic crystal structure of bilateral hollow asymmetric scatterers was proposed based on the local resonance mechanism. The energy band structure, transmission loss spectrum and intrinsic displacement field of phononic crystals with bilateral hollow asymmetric scatterers were calculated by the finite element method. The ultra-wide first complete band gap with an initial frequency of 79.4 Hz and a bandwidth of 1 065.2 Hz was obtained. Combined with an equivalent spring mass system, the vibration modes of the intrinsic displacement field of the marked points were analyzed, and the mechanism of band gap formation in phononic crystals of bilateral hollow asymmetric scatterers was revealed. Furthermore, effects of the geometric parameters such as notch angle of cladding, width of connecting short plate and height of hollow cylindrical scatterer on the first complete band gap were analyzed, and the geometric parameters of the phononic crystal were adjusted to control the band gap frequency. The results show that the initial frequency of the first complete band gap of the proposed bilateral asymmetric two-dimensional hollow scatterer phononic crystal effectively reduces to less than 80 Hz, and the bandwidth exceeds 1 000 Hz. Adjusting the structural parameters of phononic crystals can realize the coexistence of local resonance and the Bragg scattering band gap in a phononic crystal, which makes it possible for a single phononic crystal to regulate the low-frequency and high-frequency band gaps simultaneously.