Abstract: To clarify the effects of UV-B radiation on the biological characteristics of different color morphs of pea aphid Acyrthosiphon pisum (Harris), new-born nymphs of two colors (red and green) pea aphid morph were irradiated with 40 W UV-B lamp for 30 min per day for 5 days. The morphs were bred in an artificial bioclimatic chamber under strict temperature conditions of 16 ℃, 20 ℃ and 24 ℃, and in two alfalfa (“Gannong 3” and “Gannong 5”) cultivars. Development duration, mass difference and mean relative growth rate per day (MRGR) of the different color pea aphids were measured. The results suggested that UV-radiation less affected growth duration, mass difference and MRGR of red and green color pea aphid morphs in “Gannong 3” (P > 0.05) at 16 ℃. At 20 ℃, development duration of red color morphs in “Gannong 3” delayed and MRGR dropped (P < 0.05), but mass difference of red color morphs in “Gannong 3” was insignificant (P > 0.05) under UV-B radiation. At 24 ℃, development duration of green color morphs in “Gannong 3” delayed, and mass difference and MRGR of green color morphs in “Gannong 3” dropped (P < 0.05) under UV-B radiation. While at 16 ℃, UV-B radiation delayed development duration and reduced mass difference and MRGR of red color morphs in “Gannong 5” (P < 0.05), it delayed development duration and reduced mass difference and MRGR of green color morphs in “Gannong 5” (P < 0.05) at 20 ℃ and 24 ℃. The findings suggested that red and green color pea aphid morphs responded differently to UV-B radiation, which responses were relative to temperature and alfalfa variety.