Metalens is a device based on metasurfaces and metagrating,which can flexibly regulate the phase,polarization,and amplitude of light. It has the advantages of lightweight and easy-integration.However,the fabrication cycle time of metalens is long and the cost is great,and it is extremely necessary to find an easy-to-process,low-cost and high-efficient method.In this work,an all-dielectric terahertz (THz) metagrating with highly efficiency wavefront control in THz range is proposed.The all-dielectric metagrating bends the electromagnetic waves beam into the T-1 diffraction order when the electromagnetic wave is incident normally. In the simulation,more than 83.44% of the transmitted energy is concentrated in the T-1 diffraction order for P-polarized light and more than 82.73% for S-polarized light.Then,based on the all-dielectric metagrating,a metalens with numerical aperture of NA=0.39 at 0.14 THz is proposed,the metalens has been fabricated by 3D printing.The focusing capability of the metalens is characterized by utilizing the scanning measurement system.The focal spot with the focusing distance of 114.5 mm is achieved,the measured and anticipated results are satisfactorily congruous with one another,which could validate our design.Meanwhile,the size of the focal spot is obtained.The transmission THz imaging system is performed to characterize the imaging capability of the metalens.This work holds great promise for extensive applications in light sensing,communication,and super-resolution imaging.