This research was conducted in Belancan Village, Kintamani District, Bangli Regency, Bali, Indonesia, from December 2020 to July 2021, which aimed to increase production and fruits quality of Siam orange with calcitor fertilizer and concentration of neem leaf extract. The study used a randomized block design, factorial with 2 factors and 3 replications. The first factor was calcitor fertilizer consisting of 4 concentration levels, i.e., 0 cc/l/tree (K0); 2 cc/l/tree (K1), 4 cc/l/tree (K2), and 6 cc/l/tree (K3), while the second factor was neem leaf extract consisting of 3 concentration levels, i.e., 0% (M0), 5% (M1), and 10% (M2). The results showed that the interaction between calcitor fertilizer and neem leaf extract concentration had no significant effect on all observed variables. Calcitor fertilizer with a concentration of 6 cc/l/tree could improve the quality of Siam orange fruit, which was reflected by the increase in the number of fruit per tree (106.44 fruit), weight per fruit (114.08 g), weight of fruit per tree (14 .37 kg), fruit diameter (6.89 cm) and total dissolved solids (11.52 %brix) or increased by 27.56%, 7.54%; 40.74%; 12.58% and 44.72%, respectively, than those of control. While in the treatment of neem leaf extract at a concentration of 10% increase the number of fruit per tree (107.73 fruit), weight per fruit (117.44 g), fruit weight per tree (16.04 kg), fruit diameter (7.58 cm) and total dissolved solids (10.83% brix), or an increase of 69.44%; 18.76%; 78.84% and 42.31%, respectively, than those of control.