Abstract: By using testing methods of “3414” fertilizer efficiency experiment,basing on the production fact of lettuce （Lactuca sativa var ramosa Hort.） production in Northwest Guizhou Agricultural Park, the mathematical model of the relationship between N,P₂O₅,K₂O and yield was established, and the optimum fertilization per unit yield of lettuce was proposed by simulation. The result showed that N₂P₂K₂（the amplication amount of N、P₂O₅、K₂O was 210,90,150 kg/hm² repectively） had the largest yield, and was extremely significant higher than N₀P₀K₀ （no fertilizer）. The effect of N,P and K on yield was N,K,P from most significant to least significant. The largest yield was 27 226.79 kg/hm²,27 499.26 kg/hm² and 27 158.40 kg/hm² by regression analysis of unitary quadratic regression equation, when the amounts of N,P,K applied were 174.77 kg/hm², 92.63 kg/hm²,181.04 kg/hm² respectively.

Key words: “3414” experiment;, lettuce （Lactuca sativa var ramosa Hort.）, fertilizer application, yield