A novel method combining ultrasound assisted extraction with single particle inductively coupled plasma-mass spectrometry（SP-ICP-MS）was developed for the analysis of nano TiO2 in sunscreen.To obtain the optimal extraction and analysis conditions,the experimental factors such as extraction solvents,dwell time and number concentration of nano TiO2 were investigated.Result showed that the optimum dwell time was 3 ms and the upper concentration limit for nano TiO2 was 4×107 particles/mL.The nano TiO2 in sunscreen could be extracted effectively by ultrasound assisted extraction with 01% Tritonx-100 and 5% ethanol as extracting agents.The method could be used for the detection on nano TiO2 in sunscreen with a detection limit for number concentration（LODconc）of 1×104 particles/mL and a detection limit for particle size（LODsize）of 35 nm.With the advantages of simplicity,rapidness,good sensitivity and accuracy,the method could be applied in the simultaneous determination and characterization on concentration and particle size distribution of nano TiO2 in sunscreen.