Abstract: The critical surface tension (CST) of litchi leaf, as well as the surface free energy (SFE), surface tension, static contact angle and dynamic contact angle in 0-60 s of diluted solution of 10% difenoconazole water dispersible granule (WG) were determined by using contact angle measuring device and automatic surface tension meter. Effects on wettability of difenoconazole WG with adjuvants (0.4% silwet stik and 0.2% as 100) on litchi leaf surface were also investigated．The results showed that the SFE value of the adaxial surface of litchi leaf was about 23.74 mJ/m², while the SFE value of the abaxial surface was about 11.89 mJ/m², and the dispersion component was dominant．The surface tension of 500-fold dilution of 10% difenoconazole WG with 0.4% silwet stik on litchi leaf was 21.90 mN/m, while the CST of lichi leaf was 22.64 mN/m. The contact angle of WG’s 500-fold dilution with silwet stik declined the fastest during 0-10 s．The results suggested that the adaxial surface of litchi leaf was more wettable than the abaxial surface. When 10% difenoconazole WG was applied to lichi trees, the best performance was accheived by 500-fold dilution with 0.4% silwet stik adjuvant．