Abstract: Soil acidification and secondary salinization caused by fertigation are important limiting factors for soil sustainable utilization in crop production. A successive 5-year drip fertigation in litchi grown in a latosol at Chengmai county, Hainan Province during 2013—2018 was conducted to investigate the effects of different fertilizer ratios of K and N in drip fertigation (i.e. K₂O/N = 0.6, 0.8, 1.0 and 1.2, respectively) under the conventional P fertilization on soil pH and salinity in both layers of 0-30 cm and 30-50 cm, and these also as affected by different fertilization methods (i.e. the conventional P fertilization with K and N in drip fertigation, all fertilizers (N, K, Ca, Mg and B) in drip fertigation and all fertilizers in conventional fertilization) at the same ratio of K₂O/N = 1.0. The results showed that there was no close relation between the variations of soil pH, soil salinity and salty ions and the ratios of K₂O/N. However, at the end of the experiment, soil pH was reduced in the treatment of excessive N with the ratio of K₂O/N = 0.6 by promoting Ca²⁺ leaching in both soil layers. Meanwhile, drip fertigation of K and N fertilizers at the ratio of K₂O/N = 1.0 slightly increased soil pH, but by which there was no significant impact on soil salinity and salty ions. In contrast to the drip fertigation of all fertilizers, the conventional fertilization of them were beneficial to maintain soil pH due to preserve the salty cations within soil layers. Conclusively, drip fertigation of K and N fertilizers at K₂O/N = 1.0 in combination with the conventional P fertilization was recommended for the long-term litchi production to avoid soil acidification and secondary salinization even in the production areas with plentiful rainfall.