Results: The rate of children 2 - 4 years old with tooth decay was 71.4%; dmft: 5.63±5.46; dmfs: 8.58±10.27; After intervention with fluoride varnish, 47.2% of the tooth surface damaged at l stage 1 and stage 2 returned to normal, 0.31.4% of the tooth surface remained at stage 1 and stage 2, 21.4% of the tooth surface changed to worse stage 3-6.