Aims: To improve ultraviolet (UV) resistance of Bacillus thuringiensis for increasing the duration of the Bt product applied in the field, a genetically engineered strain Bt TD841 that produced both melanin and Cry1A protein was constructed, and its UV resistance was evaluated in the laboratory. Methods and Results: Melanin quantitative analysis revealed that the recombinant strain Bt TD841 could synthesize 0.15 mg melanin ml(-1) sporulated culture. Atomic force microscopy confirmed the production of diamond crystal and SDS-PAGE results showed the expression of the 130 kDa Cry1A protein. Bioassay results demonstrated that the LC50 value of Bt TD841 was 3.69 mu l ml(-1) against Helicoverpa armigera and the UV resistance of this recombinant was enhanced 9.7-fold compared to its parental strain Bt HC42 after 4-h UV irradiation. Conclusion: Expression of the mel gene can significantly increase UV resistance of B. thuringiensis. Significance and Impact of the Study: This is the first report on genetically engineered Bt strain with co-expression of melanin and the insecticidal crystal proteins gene, and the results may offer a practical solution for improving the photoprotection of Bt products in field application.