In order to achieve highly efficient nonlinear conversion through the design of optical elements, a structural unit composed of an Au nanoring, an Au split-ring resonator (SRR), and four GaAs nanorods is proposed to form a nanoring disk resonant cavity and a hybrid structure metasurface of the open resonant ring. The SRR and nanoring jointly excited Fano resonance to enhance the local electric field. The four GaAs nanorods with high second nonlinear polarizability in subatoms are used as second harmonic generation converters to reduce the absorption loss and improve the nonlinear conversion efficiency. Furthermore, the mode matching of dipole resonance at both the fundamental frequency and the second harmonic improves the nonlinear conversion efficiency. The efficiency for second harmonic generation is up to 0.15% through simulations. Therefore, this research provides new ideas for the exploration and design for novel optical components with high nonlinear conversion efficiency.