The 3p photoabsorption spectra of Ca III are analyzed with multichannel quantum defect theory (MQDT). Fitting MQDT parameters to minimize deviation between the observed and theoretical energy values, we have determined the MQDT parameters (μα,Uiα) for J=1 odd-parity MQDT model and using these parameters we predict the energies and Landé g factors of 3p5nd(3/2,3/2) (7⩽n⩽31), 3p5nd(3/2,5/2) (12⩽n⩽31), 3p5nd(1/2,3/2) (11⩽n⩽18), 3p5ns(1/2,1/2) (12⩽n⩽19), 3p5ns(3/2,1/2) (13⩽n⩽32) and autoionized energy levels of 3p5ns(1/2,1/2) (20⩽n⩽24) and 3p5nd(1/2,3/2) (19⩽n⩽23). Some assignments of levels are changed.