Abstract: Abstract: Concerning the tissue of the decay of navel oranges caused by blue and green moulds, the continuous use of fungicides has faced 2 major problems: the increasing public concern regarding fungicidal residue contamination, and the proliferation of resistance in the pathogen populations. The aim of this research was to develop the new preservative technology of navel oranges. The bioactivity of Ligusticum chuanxiong Hort extract in vivo and vitro against Penicillium italicum and Penicillium digitatum, and their effects on the quality of postharvest navel orange fruits were studied. The Ligusticum chuanxiong Hort’s rhizoma was extracted by 70% (v/v) ethanol under ultrasonic conditions. Then the concentration of the extract was adjusted for further experiments. In the in vitro experiments, the chuanxiong extract was added into potato dextrose agar (medium), and a series of chuanxiong extracts with different concentrations containing medium were developed to test the minimum inhibitory concentration (MIC) on Penicillium italicum and Penicillium digitatum. The results showed that Penicillium italicum and Penicillium digitatum were inhibited effectively in presence of the extract, and the MIC was both 25.00 g/mL. In the in vivo experiments, the fruits were wounded, inoculated with Penicillium italicum or Penicillium Digitatum, and treated with chuanxiong extract. After 1 week, the green and blue moulds incidences on treated oranges were both reduced. It demonstrated that the extract could significantly inhibit pathogen grow in the navel oranges when the concentration was 4%. The extract was further used on postharvest navel oranges, and the extract had no adverse impact on fruits. What was more, 3% and 4% extracts were good for fruits, especially the 4% extract. The results showed that, compared to the control group, the extract had a significant effect on the preservation and quality maintenance of postharvest navel oranges when the concentration was 4%. The decay time was put off, the fruit rotting rate, the weightlessness rate, and the malonaldehyde (MDA) content were significantly reduced; the activity of peroxidase (POD) was induced, the decrease of total acid content was delayed, and the contents of total sugar and total soluble solid were kept well to some extent, but it had little effect on the peel’s color and the content of vitamin C. After 100 d storage at room temperature, the fruit treated with 4% extract had the rotting rate of 5.42%, the weightlessness rate of 4.16%, the color value of 17.18, the total acid content of 0.51 g/(100 g), the vitamin C content of 52.40 mg/(100 g), the total soluble solid content of 13.9%, the total sugar content of 11.70 g/(100 g), the peroxidase activity of 8.3 u/(min•g), and the malonaldehyde content of 3.89 μmol/g. The results indicated that, applying the chuanxiong extract on postharvest navel orange fruits was simple and feasible. This research provides a reference for the exploitation of natural fungicides, and the preservation of navel oranges with Chinese medicine during storage, transportation and selling.