Abstract: The effects of leaf picking time, leaf picking type, tree age and fresh and dry leaves on oil yield were investigated in this study. The results showed that: (1) When mixed leaves of different ages were collected, the oil yield of Cinnamomum longepaniculatum aged 21-40 years was higher than that of trees aged less than 20 years and more than 41 years, and the highest oil yield occurred in April, August and December. (2) When young leaves of the same age are collected, the oil yield of spring shoots in March was the lowest, only 0.5%. (3) The difference of oil yield between fresh leaves and natural air-dried leaves of Cinnamomum longepaniculatum was small, which was 0.11%. The results indicated that the oil yield of Cinnamomum longepaniculatum leaves was related to the degree of lignification. The higher the degree of lignification, the higher the oil yield. After lignification, the oil yield was stable and the loss was small. In the production process, it is recommended that it is better to harvest Cinnamomum longepaniculatum leaves when Cinnamomum longepaniculatum is fully lignified.