【Abstract】 Objective To assess the killing efficacy of three  photosensitizers such as rose bengal（RB）, erythrosin B and  α-terthiophe to the fourth-instar larvae of Aedes albopictus in the laboratory and the field. Methods The number of dead larvae was recorded after application of RB, erythrosin B and α-terthiophen at different illumination conditions, and experimental parameters affecting photoinsecticidal was analyzed. The toxicity mechanism of RB, erythrosin B and α-terthiophen was studied by histochemistry method.  Results RB, erythrosin B and α-terthiophen showed less activity in dark .  The killing effect to larvae could reach 100% using 10 or 25 μg/ml RB and 100 or 150 μg/ml erythrosin B after exposed to 320×102 lx of light intensity generated by daylight lamp (100 W) for 6 h. The killing effect of α-terthiophen also achieved 100% at the concentration of 1 μg/ml after exposure to moderate or low intensity sunlight for 5 h. Erythrosin B and α-terthiophen was applied to control Ae.albopictus larvae in the clear water or muddy water of the field respectively. The result showed the killing rates of RB and α-terthiophen were 46% and 49% in the muddy water body, and 67% and 89% in the clear water body. However, that of α-terthiophen reached 98% in the above mentioned water body after continuously exposed to strong sunlight. Severe pathological damage of larvae caused by RB,erythrosin B and α-terthiophen were observed with optical microscopic. The damage were as follows: villus of midgut disappeared,  midgut cells swell and cell nucleus disappeared. Fat body widely distributed under the epidermis and the shape of malpighian tubes was abnormal and its lumens narrowed. Conclusion RB, erythrosin B and α-terthiophen are high?efficiency and applied photo-insecticides.