In this work, we propose a DNA hybridization detection platform with assembled magnetic beads and integrated photodiodes on a silicon chip. DNA targets labeled magnetic beads generate an opaque area after hybridization, and the fabricated photodiode is utilized to turn ordinary light into electricity. Compared with the detected photocurrent before hybridization, the signal of DNA hybridization can be distinctly diagnosed by the light intensity changing. As far as we know, it is the first time to assemble magnetic beads with integrated photodiode on a silicon chip to detect DNA hybridization. The advantages of this detection platform are lower cost, higher precision and less time consuming. With this technique, we could successfully discriminate single base mismatched DNA from perfectly matched DNA sequence, which saves the time of amplifying hybridization signal. This detection platform also fits for DNA computing because magnetic property could easily eliminate unfeasible solutions of problem. The experimental result of a minimum vertex cover problem, which is solved by DNA computing on this platform, reveals the obvious benefits of this detection platform and its potential to be used to construct a fully automatic DNA computer with photoelectric readout.