The dipole-length, velocity and acceleration absorption oscillator strengths for the 1s22p-1s2nd (3 ≤ n ≤9) transitions of the lithium-like systems with Z=1 1 to 20 are calculated using the energies and the multiconfiguration interaction wavefunctions obtained from a full core plus correlation method. The agreement between the f-values calculated from the length, velocity and acceleration formulae is excellent. Our results agree closely with the experimental data avail able in the literature. Combining these discrete oscillator strengths with the single-channel quantum defect theory,the discrete oscillator strengths for the transitions from 1s22p state to highly excited states (n ≥10) and the oscillator strength densities corresponding to the bound-free transitions are obtained.