This　study　investigated　the　fabrication　of　a　strengthened　Ti-TiO2　material　with　adding　0.5　wt.%　TiO2　nanoparticles　via　selective　laser　melting　process　in　comparison　with　CP-Ti.　Through　the　process　parameters　optimized　by　response　surface　methodology,　the　Ti-TiO2　material　fabricated　by　SLM　showed　remarkable　tensile　strength　of　800.6　MPa　and　elongation　of　14%,　as　compared　to　the　fabricated　CP-Ti　with　tensile　strength　of　594.0　MPa　and　elongation　of　21%.　The　x-ray　diffraction　patterns　of　fabricated　specimens　showed　the　expansion　of　the　hcp-Ti　lattice　along　the　c-axis　due　to　dissolved　oxygen　atoms　from　the　decomposition　of　TiO2　nanoparticles.　The　microstructure　analysis　observed　remains　of　incompletely　decomposed　TiO2　and　TiO　phases　in　SLMed　Ti-TiO2　material,　which　was　distinguished　from　former　studies.　Consequently,　the　decomposition　behavior　of　added　TiO2　nanoparticles　associated　with　the　dissolved　oxygen　in　the　Ti-matrix　during　the　SLM　process　was　discussed.　Based　on　the　evaluation　of　both　the　solution　effect　of　oxygen　atoms　and　the　reinforcing　effect　of　undecomposed　nanoparticles,　the　dissolved　oxygen　from　decomposed　TiO2　was　considered　the　primary　factor　in　the　intensified　strength　of　SLMed　Ti-TiO2　material.　These　results　could　offer　novel　insights　into　the　additive　manufacturing　of　high-strength　and　biocompatible　titanium　alloy　via　the　SLM　process.