Abstract: In order to provide theoretical foundation and scientific guidance for Macadamia production in dry hot valley area of Yunnan Province, the fruit growth and drop law of Macadamia nut were studied. 3 Macadamia cultivars‘HASE695’,‘HASE900’and‘Own Choice’were used as materials, and the fruit growth and fruit characteristics were investigated. The results showed that the key period of Macadamia fruit swelling was from mid to late April to mid May, with an increase of 1.38- 1.54 cm in fruit diameter. In Lujiangba dry and hot river valley area, there were 2 peaks of Macadamia fruit dropping. The major cause of the first dropping peak was poor pollination, poor fertilization and fruit rapid growth of malnutrition; the second dropping peak was mainly manifested as premature drop, the fruit droping rates of‘HASE695’,‘HASE900’ and‘Own Choice’in this period were 2.7%, 2.11% and 4.51%, and the Macadamia fruit reached a constant size in this period. In this study, we found that further study on Macadamia fruit retention measures should be mainly aimed at the second fruit dropping peak with the purpose of reducing dorp rate and increasing yield.