Kernel characteristics, oil contents, fatty acid compositions and biodiesel properties were studied in developing Siberian apricot (Prunus sibirica L.) seeds, at intervals of 1 week from 3 weeks after anthesis to 10 weeks. Variation of kernel dry biomass, kernel length, kernel breadth and kernel thickness were significant (P<0.01). Oil content increased with maturity and reached the highest point at 8 weeks after anthesis (51.6%). Changes in the content of oleic acid (C18:1) and linoleic acid (C18:2) presented an opposite trend that oleic acid increased, whereas linoleic acid decreased until 7 weeks after anthesis. Siberian apricot methyl esters meet the specifications better in biodiesel standards when seeds were harvested at 8, 9 and 10 weeks after anthesis. Siberian apricot seeds harvested after 8 weeks after anthesis may be suitable for producing biodiesel.