Abstract: 【Objective】Active oxygen quantum yield, insecticidal activities and stability of diphenylthiophene were compared to α-terthienyl in a study for the first time. 【Result】The results showed that absorbency variety max of diphenylthiophene was 0.438 after ultraviolet irradiation for 280 min while α-terthienyl absorbency variety max was 0.480 after ultraviolet irradiation for 200 min. LC50 value of diphenylthiophene and α-terthienyl against 3rd instar larvae of Aedes albopictus was 9.18×10-3 μg·ml-1 and 9.69×10-4 μg·ml-1 after 24 h of treatment. LC50 value of the two pesticides against 3rd instar larvae of Plutella xylostella was 267.87 μg·ml-1 and 222.22 μg·ml-1 after 24 h of treatment. The half-life of diphenylthiophene and α-terthienyl in methanol was 113.62 h and 10.49h. Quantum yield of diphenylthiophene and α-terthienyl was almost identical and they all had high toxicity to Aedes albopictus and Plutella xylostella, but diphenylthiophene was stable than α-terthienyl. 【Conclusion】It is concluded that diphenylthiophene has avoided the deficiency of photoactivated insecticides which degraded quickly in the environment and could not apply in the farm. On the one hand diphenylthiophene could kill the insects, on the other hand diphenylthiophene could accelerate the degradation ratio of triazophos. Diphenylthiophene is worth exploiting and applying in the field.

Key words: Diphenylthiophene, Quantum yield, Insecticidal activities, Stability