Abstract: Coconut was an important tropical oil crop. The main component in coconut oil was lauric acid. Based on coconut solex sequencing, 11 acyl-ACP thioesterase genes were identified, including 2 FatA genes, 4 FatB1 genes, 3 FatB2 genes and 2 FatB3 genes. The expression level of 5 unigenes, Unigene9211, Unigene19303, Unigene45926, Unigene27250 and Unigene22278, were detected using real time PCR. These detected unigenes related to acyl -ACP thioesterase were found to be sustainably expressed during three developmental stages of coconut fruit. Meanwhile, the fatty acid component during three developmental stages of coconut fruit was examined using GM/MS. In seven month after pollination, low to medium chain fatty acid had comparative low proportion. Subsequently,the content of low-medium chain fatty acid gradually increased.