Abstract: Plant protection is a weak link in the whole mechanization of rice production in China.Contrast test on two plant protection modes of unmanned aerial vehicle（UAV）and semi-mechanization for rice was carried out.Results showed that UAV efficiency was 16 times that of semi-mechanized operation，saved pesticide costs 26.4% and saved total cost per unit area 23.42%.At the same time，UAV had the advantages of uniform spraying，good atomization effect，good environmental protection effect and high safety factor.UAV plant protection of rice would be one of the important models to replace traditional semi-mechanized operation.