Abstract: Phononic crystals with elastic wave bandgap properties have found broad application in the development of new functional material for vibration isolation and noise suppression. A kind of phononic crystal structure in square lattice with connectors is improved to obtain a wide frequency bandgap. The bandgap properties and the vibration mode of the phononic crystals in different structural configurations are simulated and analyzed using the finite element method. The numerical results show that the improved structures display a single wide frequency bandgap with the relative bandgap width more than 100% within the frequency range of initial separated bandgaps. The reason fbr the occurrence of the single bandgap is the suppression of the free vibration mode of original connectors, resulting from the simultaneous introduction of the mass and connectors in unit cell. Moreover, the bandgap properties can be manipulated by changing the geometry size, the number of connectors and the symmetry of the structure.