As an important pest, Tetranychus urticae fed on thousands of host plants and showed strong capability in host adaptation. However, hardly any success artificial diet has been developed for it. In this study, we compared adult longevity and reproduction of T. urticae that fed on its natural food (bean leaves) and an artificial diet with leaf extracts added, and tried to investigate the reason why the artificial diet was inefficient through transcriptome analyses. Mean adult longevity and cumulative fecundities of T. urticae was reduced by 53.4% and 93.8%, respectively. Transcriptome analyses showed that 1731 genes were differentially expressed comparing individuals fed with the artificial diet and with their natural food, among which most (77.1%) were down regulated. No significant induced expression of xenobiotic transporters and detoxification enzymes were observed when T. urticae were fed with the artificial diet. In contrast, differentially expressed genes were mainly enriched in digestive related terms, especially in lipid metabolism related pathways, with most genes down regulated. Our results indicated the significance in further investigating lipid demand and metabolism of T. urticae to improve its mass rearing techniques.