Active oxygen quantum yield,insecticidal activities and stability of diphenylthiophene were studied for the first time.The results showed that maximum diphenylthiophene absorbency variety was 0.438 after irradiation for 280 min and that ofα- terthienyl(α-T)was 0.480 after irradiation for 200 min with UV.LC 50 values of diphenylthiophene andα-T against 3rd instar larvae of Aedes albopictus were 9.18×10-3 and 9.69×10-4μg mL-1 when treated for 24 h,respectively.LC 50 values of the two chemicals against the 3rd instar larvae of Plutella xylostella were 267.87 and 222.22μg mL-1 when treated for 24 h, respectively.The half lives of diphenylthiophene andα-T in methanol were 113.62 and 10.65 h.Difference between quantum yield of diphenylthiophene andα-T was not significant and they all possessed high toxicity to Aedes albopictus and Plutella xylostella,but diphenylthiophene was more stable thanα-T.It could be concluded that diphenylthiophene has overcome the deficiency of photoactivated insecticides which degraded quickly in the environment and could not be applied on the field.Diphenylthiophene could kill the insects and accelerate the degradation rate of triazophos.The benefits of diphenylthiophene can be further exploited and applied on the field. Active oxygen quantum yield, insecticidal activities and stability of diphenylthiophene were studied for the first time. The results showed that maximum diphenylthiophene absorbency variety was 0.438 after irradiation for 280 min and that of α-terthienyl (α-T) was 0.480 after irradiation for 200 min with UV.LC 50 values ​​of diphenylthiophene and α-T against 3rd instar larvae of Aedes albopictus were 9.18 × 10-3 and 9.69 × 10-4 μg mL-1 when treated for 24 h, respectively. LC 50 values ​​of the two chemicals against the 3rd instar larvae of Plutella xylostella were 267.87 and 222.22 μg mL-1 when treated for 24 h, respectively. These half lives of diphenylthiophene and α-T in methanol were 113.62 and 10.65 h. Difference between quantum yield of diphenylthiophene and α-T was not significant and they all possessed high toxicity to Aedes albopictus and Plutella xylostella, but diphenylthiophene was more stable than α-T.It could be concluded that diphenylthiophene has overcome the deficiency of photoactiva ted insecticides which degraded quickly in the environment and could not be applied on the field. Diphenylthiophene could kill the insects and accelerate the degradation rate of triazophos. The benefits of diphenylthiophene can be further exploited and applied on the field.