Currently,　great　challenges　to　top-down　phosphoproteomics　lie　in　the　selective　enrichment　of　intact　phosphoproteins　from　complex　biological　samples.　Herein,　we　developed　a　facile　approach　for　synthesis　of　Ti4+-immobilized　affinity　silica　nanoparticles　and　applied　them　to　the　selective　separation　and　enrichment　of　intact　phosphoproteins　based　upon　the　principle　of　metal(IV)　phosphate/phosphonate　chemistry.　The　as-prepared　affinity　materials　exhibited　high　selectivity　and　adsorption　capacities　for　model　phosphoproteins　(328.9　mg/g　for　beta-casein,　280.5　mg/g　for　ovalbumin,　and　225.8　mg/g　for　alpha-casein),　compared　with　nonphosphoproteins　(79.28　mg/g　for　horseradish　peroxidase,　72.70　mg/g　for　BSA,　and　27.28　mg/g　for　lysozyme).　In　addition,　the　resuability　of　the　affinity　silica　nanoparticles　was　evaluated,　and　the　results　demonstrated　a　less　than　10%　loss　of　adsorption　capacity　after　six　adsorption-regeneration　cycles.　The　practicability　of　the　affinity　materials　was　demonstrated　by　separating　phosphoproteins　from　protein　mixtures　and　drinking　milk　samples,　and　the　satisfactory　results　indicated　its　potential　in　phosphoproteomics　analysis.