We propose a design and numerical study of an optically blueshift and redshift switchable metamaterial (MM) absorber in the terahertz regime.The MM absorber comprises a periodic array of metallic split-ring resonators (SRRs) with semiconductor silicon embedded in the gaps of MM resonators.The absorptive frequencies of the MM can be shifted by applying an exteal pump power.The simulation results show that,for photoconductivity of silicon ranging between 1 S/m and 4000S/m,the resonance peak of the absorption spectra shifts to higher frequencies,from 0.67THz to 1.63 THz,with a resonance tuning range of 59％.As the conductivity of silicon increases,the resonance frequencies of the MM absorber are continuously tuned from 1.60THz to 1.16 THz,a redshift tuning range of 28％.As the conductivity increases above 30000S/m,the resonance frequencies tend to be stable while the absorption peak has a merely tiny variation.The optical-tuned absorber has potential applications as a terahertz modulator or switch.