In order to systematically study the predatory behavior and digestion regularity of spiders, real-time fluorescence quantification PCR technique was used to detect the number of CO-I genes in Pardosa pseudoannulata after it preyed on rice planthoppers in different temperatures within different periods. At 28 °C, 0, 1, 2, 4, 8, 16, and 24 h after P. pseudoannulata preyed on rich planthopper, DNA was extracted from cephalothorax and abdomen of P. pseudoannulata. Routine PCR and real-time fluorescence PCR techniques were employed for CO-I gene amplification. The results show that: The prey liquid was temporarily stored in the sucking stomach of the spider head within 2 h after prey, and gradually transferred to the midgut of the abdomen with the prolongation of time. After 4 h, CO-I gene residues of rice planthopper in the cephalothorax gradually decreased. The CO-I gene of rice planthopper was basically transferred to the abdomen after 16 h. During 0–1 h, food contained in abdominal midgut and other digestive organs was very small, CO-I gene detection was not obvious. Over time, food entered into the midgut from the sucking stomach for digestion. During 2–4 h, CO-I gene amount increased, at 2–4 h, detected CO-I gene residue reached the peak; but rapidly declined after 8, 16, and 24 h, even it is still detectable. The results at different temperatures reveal that: As the temperature increased from 26 °C to 32 °C, CO-I gene residues of rich planthopper in cephalothorax and abdomen of P. pseudoannulata gradually decreased, which indicated that the digestion rate increased with the increase of temperature with some range. However, when the temperature continued to increase to 34 °C, the digestion rate decreased.