Abstract: In order to explore the influence of fertilization on the combustibility of coniferous species, fertilization experiments were carried out on 4 major coniferous tree species-Pinus yunnanensis, P. armandi, P. yunnanensis var. pygmaea, and Cupressus torulosain the Yuanbaoshan forest area of Yunnan Forest Nature Center, Panlong District, Kunming City from 2013 to 2018. According to the principle of proximity, 40 plants were selected for each tree species, and 10 plants were applied with phosphate fertilizer, nitrogen fertilizer, potash fertilizer and compound fertilizer respectively. Another 10 unfertilized plants for each tree species were selected as control group. In December of 2017 and 2018, samples were taken to text the crude fat content, ash content and calorific value of the 4 coniferous species both fertilized and unfertilized. The principal component analysis method was used to determine the weight of the evaluation index, and the combustibility of needles was determined by calculating the comprehensive index of combustibility. Compared with the control group, the average increase rates of the crude fat content, ash content, and calorific value of the 4 kinds of needles after phosphate fertilizer application were 17. 05%, 1. 27%, and 3. 55% respectively. The average increase rates of the 3 indicators after nitrogen fertilizer application were 8. 29%,-11. 63%, and 2. 85% respectively. The average increase of the 3 indicators after potassium fertilizer application were 11. 09%,-4. 32%, and 1. 94% respectively. The average increase of the 3 indicators after applying compound fertilizer were 18. 19%,-3. 35%, and 1. 63% respectively. Except for P. armandii needles treated with potassium fertilizer, the comprehensive flammability index of other experimental groups was higher than control group, and the average combustibility composite index of phosphate fertilizer, nitrogen fertilizer, potash fertilizer and compound fertilizer and control group was 0. 591,0. 577, 0. 570, 0. 578 and 0. 498 respectively. After fertilization, the crude fat content and calorific value of the needles showed an overall increasing trend, the ash content of the needles showed a downward trend when nitrogen fertilizer and compound fertilizer were applied, and there was no obvious change trend for the ash content when phosphate and potassium fertilizers were applied. Comprehensive analysis showed that:（1） The application of 4 kinds of chemical fertilizers increased the flammability of the needles of Pinus yunnanensis, P. yunnanensis var. pygmaea, and Cupressus torulosa. While the application of potassium fertilizer reduced the flammability of the needles of P. armandi, and the application of the other 3 kinds of chemical fertilizers improved the flammability of the needles of P. armandi.（2） The effects of the 4 fertilizers on the flammability from high to low rules of needles in 2017 and 2018, P. yunnanensis var. pygmaea showed that potash fertilizer ＞ phosphate fertilizer ＞ nitrogen fertilizer ＞ compound fertilizer. The impact results of the other 3 tree species in 2017 and 2018 showed different rules.（3） The effects of fertilizing on flammability from high to low rules of 4 tree needles showed that phosphate fertilizer ＞ compound fertilizer ＞ nitrogen fertilizer ＞ potash fertilizer.