Three dye lasers are used to excited Sr atoms to obtain ions and electrons through autoionization process. The wavelength of the second laser is scanned when those of the first and third lasers are fixed, through which spectra of Sr 5sns 1S 0 and 5snd 1, 3 D 2 series are measured. Experimental spectra are described and analyzed by multichannel quantum defect theory, which verifies measured data and predicts unmeasured data with their energies and wave functions. The study also provides radiative lifetimes of highly-excited states. Agreement between the theory and experiment is achieved. This work also agrees well with previons studies.